Distributed electrode array for plasma processing

ABSTRACT

Embodiments of the disclosure provide a plasma source assembly and process chamber design that can be used for any number of substrate processing techniques. The plasma source may include a plurality of discrete electrodes that are integrated with a reference electrode and a gas feed structure to generate a uniform, stable and repeatable plasma during processing. The plurality of discrete electrodes include an array of electrodes that can be biased separately, in groups or all in unison, relative to a reference electrode. The plurality of discrete electrodes may include a plurality of conductive rods that are positioned to generate a plasma within a processing region of a process chamber. The plurality of discrete electrodes is provided RF power from standing or traveling waves imposed on a power distribution element to which the electrodes are connected.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 62/543,769, filed Aug. 10, 2017, which is herein incorporatedby reference.

BACKGROUND Field

Embodiments of the present disclosure generally relate to semiconductorprocessing equipment. More particularly, embodiments of the presentdisclosure relate to an electrode assembly that is used to generate aplasma to process a substrate.

Description of the Related Art

Integrated circuits have evolved into complex devices that can includemillions of components (e.g., transistors, capacitors, resistors, andthe like) on a single chip. The evolution of chip designs requiresfaster circuitry as well as greater circuit density, and the demand forgreater circuit density necessitates a reduction in the dimensions ofthe integrated circuit components. The minimal dimensions of features ofsuch devices are commonly referred to in the art as critical dimensionsand generally include the minimal widths of the features of the circuitstructure, such as lines, spaces between the lines, columns, openings,and the like.

As these critical dimensions shrink, process uniformity across thesubstrate becomes important in order to maintain high yields.Conventional plasma processes and conventional chamber designs that areused to manufacture increasing smaller geometry integrated circuits thatare required today are not able to meet the deposition or etch rateuniformity requirements needed across the entire substrate during plasmaprocessing which is essential for successful semiconductor devicefabrication. Such uniformity is becoming more difficult to achieve asdevice geometries are shrinking and substrate sizes are increasing.Various sources of process non-uniformity, such as chamber designasymmetries, temperature distribution non-uniformities and gasdistribution control are becoming more important. Also, conventionalcapacitively-coupled plasma sources (CCPs) and inductively-coupledplasma sources (ICPs) suffer from several issues, which includeundesirable plasma and process uniformity, and poor processrepeatability. For example, conventional inductively coupled plasmasources can have two concentrically arranged coil antennas over thechamber ceiling, so that uniformity of etch rate distribution can beoptimized by adjusting the different RF power levels delivered to thedifferent coil antennas. But, as workpiece diameter and chamber diameterincrease, we have found this approach is not adequate, as the largersize increases the difficultly of attaining the requisite processuniformity. Also, in both conventional CCP and ICP plasma sources,undesired material sputtering or etching may result in processcontamination or particle formation, which may be due to excessive ionenergy at the driven or grounded electrode surface or ICP windowsurface.

In some plasma process chambers or systems, a workpiece is moved througha plasma processing region on, for example, on a linear or rotatingworkpiece support. In such a chamber, the moving workpiece supportcircuit may not be a low impedance (relative to plasma impedance) RFground path, even though it may be DC grounded, through for example, arotary mercury coupler, brushes or slip rings. The lack of an adequateRF ground path may make it difficult to control ion energy at theworkpiece or make repeatability of the plasma process (e.g., depositionor etching process) poor.

Therefore, there is need for a plasma source and/or process chamber thatcan efficiently produce a uniform plasma that has desirable properties(e.g., degree of dissociation, composition, radical density or flux, iondensity, electron density, electron temperature, ion energydistribution, etc), is tunable over the operating window, has a stableand repeatable performance, does not generate particles, and has anacceptable hardware lifetime.

SUMMARY

A plasma source assembly for a process chamber is provided that in oneembodiment includes a plurality of discrete electrodes that arepositioned relative to a reference electrode, and in some case relativeto a gas feed structure, to generate a uniform, stable and repeatableplasma during processing.

Embodiments of the disclosure provided herein include a plasma sourceassembly, including a reference electrode having an electrode surfacethat is distributed across a first plane, and an array of discreteelectrodes that are arranged in a pattern that is distributed across thefirst plane. The pattern of discrete electrodes can be formed in anarray that is distributed in two non-parallel directions that are bothparallel to the first plane. The discrete electrodes can be alignedparallel to a first direction that is oriented at an angle to the firstplane, and have an end that is disposed a first distance from thesurface in a direction that is substantially perpendicular to the firstplane.

Embodiments of the disclosure may further provide a plasma sourceassembly that includes a power distribution element connected to theplurality of discrete electrodes, wherein the discrete electrodes arearranged in a pattern that is distributed across a surface, and each ofthe discrete electrodes includes an end that is disposed a firstdistance from the surface in a direction that is substantiallyperpendicular to the surface. The plasma source assembly will alsoinclude an RF signal generator that provides RF power, and a matchingnetwork that receives the RF power from the RF signal generator andprovides RF power to at least two connection points on the powerdistribution element.

Embodiments of the disclosure may further provide a plasma sourceassembly that includes a power distribution element connected to theplurality of discrete electrodes to provide RF power to the plurality ofdiscrete electrodes, wherein the discrete electrodes are arranged in apattern that is distributed across a surface, and each of the discreteelectrodes includes an end that is disposed a first distance from thesurface in a direction that is substantially perpendicular to thesurface. The plasma source assembly will also include a first RFgenerator having an input that receives a first RF control signal and anoutput that provides RF power to a first connection point on the powerdistribution element, a second RF generator having an input thatreceives a second RF control signal and an output that provides RF powerto a second connection point on the power distribution element, a phasedetector that is configured to detect a difference in the phase of theoutput from the first RF generator and the output from the second RFgenerator, and a phase controller that receives the detected phasedifference from the phase detector and generates a phase shift controlsignal that is used to alter the phase of the output delivered from thefirst RF generator.

Embodiments of the disclosure may further provide a plasma sourceassembly that includes a power distribution element connected to theplurality of discrete electrodes to provide RF power to the plurality ofdiscrete electrodes, wherein the discrete electrodes are arranged in apattern that is distributed across a surface, and each of the discreteelectrodes includes an end that is disposed a first distance from thesurface in a direction that is substantially perpendicular to thesurface. The plasma source assembly will also include a first RFgenerator having an input that receives a first RF control signal and anoutput that provides RF power to a first connection point on the powerdistribution element, a second RF generator having an input thatreceives a second RF control signal and an output that provides RF powerto a second connection point on the power distribution element, a phaseshifter that provides the first RF control signal to the input of thefirst RF generator in response to a phase shift control signal and asecond RF control signal, a signal generator that provides the second RFsignal to the phase shifter and to the input of the second RF generator,a phase detector that is configured to detect a difference in the phaseof the output from the first RF generator and the output from the secondRF generator, and a phase controller that receives the detected phasedifference from the phase detector and provides the phase shift controlsignal to the phase shifter to alter the phase of the first RF signal.

Embodiments of the disclosure may further provide a plasma sourceassembly that includes a power distribution element connected to theplurality of discrete electrodes to provide RF power to the plurality ofdiscrete electrodes, wherein the discrete electrodes are arranged in apattern that extends across a surface, and each of the discreteelectrodes includes an end that is disposed a first distance from thesurface in a direction that is substantially perpendicular to thesurface. The plasma source assembly will also include a first circulatorthat includes a first, a second and a third port, the second portproviding RF power at a first position to the power distribution elementvia a first matching network, and the third port connected to a firstdummy load, a second circulator that includes first, second and thirdports, the second port providing RF power at a second position on thepower distribution element via a second matching network, and the thirdport connected to a second dummy load, a first RF generator having thatprovides RF power to the first port of the first circulator at a firstfrequency, and a second RF generator having that provides RF power tothe first port of the second circulator at a second frequency.

Embodiments of the disclosure may further provide a method of forming aplasma in a processing region of a process chamber that includesdelivering RF power to a plurality of discrete electrodes from a firstRF generator, wherein delivering RF power from the first RF generatorcomprises providing RF power to a first connection point on a powerdistribution element that is coupled to the plurality of discreteelectrodes, and each of the plurality of discrete electrodes comprise anend that is disposed a first distance from the surface in a directionthat is substantially perpendicular to the surface, delivering RF powerto a plurality of discrete electrodes from a second RF generator,wherein delivering RF power from the second RF generator comprisesproviding RF power to a second connection point on the powerdistribution element, and controlling a phase of the RF power deliveredto the power distribution element from the first RF generator relativeto the phase of the RF power delivered to the power distribution elementfrom the second RF generator.

Embodiments of the disclosure may further provide a method of forming aplasma in a processing region of a process chamber that includesdelivering a first RF signal to a plurality of discrete electrodes,wherein delivering the first RF signal comprises delivering an RFcurrent or applying an RF voltage to a first connection point on a powerdistribution element that is coupled to the plurality of discreteelectrodes that comprise an end that is disposed a first distance fromthe surface in a direction that is substantially perpendicular to thesurface, delivering a second RF signal to the plurality of discreteelectrodes, wherein delivering the second RF signal comprises deliveringan RF current or applying an RF voltage to a second connection point onthe power distribution element that is coupled to the plurality ofdiscrete electrodes, and selecting a frequency of the first RF signaland a frequency of the second RF signal such that the delivery of firstRF signal and the second RF signal to the plurality of discreteelectrodes generates a plasma in the processing region, wherein thefrequency of the first RF signal is different from the frequency of thesecond RF signal.

Embodiments of the disclosure may further provide a method of forming aplasma in a processing region of a process chamber that includesdelivering a first RF signal to a plurality of discrete electrodes,wherein delivering the first RF signal comprises delivering an RFcurrent or applying an RF voltage to a first connection point on a powerdistribution element that is coupled to the plurality of discreteelectrodes, wherein each of the plurality of discrete electrodescomprise an end that is disposed a first distance from a surface of areference electrode in a direction that is substantially perpendicularto the surface, and delivering the first RF signal to the plurality ofdiscrete electrodes so that a travelling wave is formed in the powerdistribution element and a plasma is formed in the processing region.

Embodiments of the disclosure may further provide a plasma sourceassembly including a reference electrode having an electrode surface,wherein the electrode surface has a central axis that is perpendicularto the electrode surface at a center point. The plasma source will alsoinclude an array of discrete electrodes that are arranged in a patternthat is distributed in at least two non-parallel directions that areboth parallel to a first plane, which is perpendicular to the centralaxis, wherein each of the discrete electrodes have a length that isaligned parallel to a first direction that is oriented at an anglegreater than zero to the first plane, and each of the discreteelectrodes includes an end that is disposed a first distance from theelectrode surface, wherein the first distance is measured in a directionthat is substantially perpendicular to the first plane. In someembodiments at least a portion of each of the discrete electrodes in thearray of discrete electrodes extends through an opening formed throughthe reference electrode. In some embodiments at least a portion of thereference electrode surrounds each of the discrete electrodes in thearray of discrete electrodes. In some embodiments each of the discreteelectrodes has an outer surface that has a discrete electrode surfacearea that comprises an area of the outer surface disposed from the endof the discrete electrodes to the electrode surface, the electrodesurface has an reference electrode surface area, and a ratio of the sumof all of the discrete electrode surface areas to the referenceelectrode surface area is between 0.8 and 1.2. In some embodiments theplasma source assembly further comprises a perforated plate having aplurality of openings formed through a perforated surface of theperforated plate, wherein the plurality of openings are arranged in apattern that is configured to provide a desired gas flow distributionacross the perforated surface when a gas is delivered through theplurality of openings and wherein the electrode surface is substantiallyparallel to the perforated surface of the perforated plate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1A is a cross-sectional view an illustrative process chamber,according to an embodiment of the disclosure provided herein.

FIG. 1B is a cross-sectional view of a portion of the lower chamberassembly as viewed from the section-line shown in FIG. 1A, according toan embodiment of the disclosure provided herein.

FIG. 2A is a schematic side cross-sectional view of a portion of theupper chamber assembly illustrated in FIG. 1A, according to anembodiment of the disclosure provided herein.

FIG. 2B is a side cross-sectional view of a portion of the lid assemblyillustrated in FIG. 2A, according to an embodiment of the disclosureprovided herein.

FIG. 2C1 is a plan view of one configuration of the electrode assemblyillustrated in FIG. 2A, according to an embodiment of the disclosureprovided herein.

FIG. 2C2 is a plan view of another configuration of the electrodeassembly illustrated in FIG. 2A, according to an embodiment of thedisclosure provided herein.

FIG. 2D is a bottom view of a portion of a lid assembly of the upperchamber assembly, according to an embodiment of the disclosure providedherein.

FIG. 2E is a bottom view of a portion of a differently configured lidassembly of the upper chamber assembly, according to an embodiment ofthe disclosure provided herein.

FIG. 2F is another bottom view of a portion of a differently configuredlid assembly of the upper chamber assembly, according to an embodimentof the disclosure provided herein.

FIG. 2G is a bottom view of a portion of a lid assembly of the upperchamber assembly which schematically illustrates a relationship of areference electrode element and the array of discrete electrodes,according to an embodiment of the disclosure provided herein.

FIG. 2H is a bottom view of a portion of a lid assembly that includes apartial section view of a discrete electrode, according to an embodimentof the disclosure provided herein.

FIG. 2I is a schematic side cross-sectional view of a portion ofdiscrete electrodes illustrated in FIG. 2B, according to an embodimentof the disclosure provided herein.

FIG. 2J is a schematic side cross-sectional view of a portion of adiscrete electrode illustrated in FIG. 2B, according to an embodiment ofthe disclosure provided herein.

FIG. 2K is a side cross-sectional view of a portion of a discreteelectrode illustrated in FIG. 2J, according to an embodiment of thedisclosure provided herein.

FIG. 2L is a side cross-sectional view of a portion of a discreteelectrode illustrated in FIG. 2J, according to an embodiment of thedisclosure provided herein.

FIG. 2M is a side cross-sectional view of a portion of a discreteelectrode illustrated in FIG. 2J, according to an embodiment of thedisclosure provided herein.

FIG. 2N is a bottom view of a portion of a lid assembly of the upperchamber assembly which schematically illustrates a relationship of areference electrode element and the array of discrete electrodes,according to an embodiment of the disclosure provided herein.

FIG. 3A is a side schematic cross-sectional view of a portion of the lidassembly, according to an embodiment of the disclosure provided herein.

FIG. 3B is a side schematic cross-sectional view of a portion of the lidassembly, according to an embodiment of the disclosure provided herein.

FIG. 4A is a schematic diagram depicting a system for driving theplurality of discrete electrodes, according to an embodiment of thedisclosure provided herein.

FIG. 4B is a schematic diagram depicting a system for driving theplurality of discrete electrodes using two sources of RF power,according to an embodiment of the disclosure provided herein.

FIG. 5A is a schematic diagram depicting a system for driving theplurality of discrete electrodes, according to an embodiment of thedisclosure provided herein.

FIG. 5B is a schematic diagram depicting a system for driving theplurality of discrete electrodes using three sources of RF power,according to an embodiment of the disclosure provided herein.

FIG. 6A is a schematic diagram depicting a system for driving theplurality of discrete electrodes, according to an embodiment of thedisclosure provided herein.

FIG. 6B is a schematic diagram depicting a system for driving theplurality of discrete electrodes using three sources of RF power,according to an embodiment of the disclosure provided herein.

FIG. 7A is a schematic diagram depicting a system for driving theplurality of electrodes, according to an embodiment of the disclosureprovided herein.

FIG. 7B depicts a physical arrangement of the power distribution elementillustrated in FIG. 7A, according to an embodiment of the disclosureprovided herein.

FIG. 8A is a schematic diagram depicting a system for driving theplurality of discrete electrodes, according to an embodiment of thedisclosure provided herein.

FIG. 8B is a schematic diagram depicting a system for driving theplurality of discrete electrodes, according to an embodiment of thedisclosure provided herein.

FIG. 9 is a schematic side cross-sectional view of a portion of theupper chamber assembly illustrated in FIG. 1A, according to anembodiment of the disclosure provided herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Embodiments of the disclosure provide a plasma source assembly andprocess chamber design that can be used for any number of substrateprocessing techniques. The plasma source assembly described herein isparticularly useful for performing a plasma assisted dry etch process ora plasma assisted deposition process. The plasma source assembly may beutilized in deposition or etch process chambers available from AppliedMaterials, Inc. of Santa Clara, Calif., but may also be suitable for usein chambers for performing other types of plasma processes as well aschambers available from other manufacturers. In some embodiments of thedisclosure provided herein, the plasma source includes a plurality ofdiscrete electrodes that are integrated with a reference electrode and agas feed structure to generate a uniform, stable and repeatable plasmaduring processing. As is discussed further below, the plasma source hasthe ability to control the degree of gas dissociation, active speciescomposition, radical density, radical flux, ion density, ion flux,electron density, electron temperature, ion energy distribution, andother desirable properties within the generated plasma by controllingthe way that radio frequency (RF) power is delivered to the discreteelectrodes and controlling the gas flow characteristics within theprocessing region of a process chamber. The plurality of discreteelectrodes includes electrodes that can be biased separately, in groups,or all in unison relative to a reference electrode. In some embodimentsof the disclosure, as illustrated in FIGS. 1A and 2A-2G, the pluralityof discrete electrodes include a plurality of conductive rods that arepositioned to generate a plasma within a processing region of a processchamber.

FIG. 1A is a cross-sectional view of a process chamber 100 that includesa plurality of discrete electrodes 165 that are adapted to generate aplasma 111 in a processing region 110 of the process chamber 100. Theprocess chamber 100 generally includes an upper chamber assembly 20, alower chamber assembly 30 and a system controller 50. The upper chamberassembly 20 generally includes a lid assembly 200, an electrode assembly160, a fluid source assembly 180 and an RF source assembly 150. As isdiscussed further below, the lower chamber assembly 30 generallyincludes a chamber body 105 and a support assembly 115. FIG. 1B is across-sectional view of a portion of the lower chamber assembly 30 asviewed from the section-line shown in FIG. 1A.

FIG. 2A is a cross-sectional view of portions of the lid assembly 200and the electrode assembly 160 according to the disclosure providedherein. The electrode assembly 160 includes a plurality of discreteelectrodes 165 that are each coupled to the RF source assembly 150through one or more power distribution elements 161. The discreteelectrodes 165 are typically distributed in a pattern, such as an arrayformed across a plane (e.g., X-Y plane), that is aligned and/or orientedrelative to the surface 226 of the lid assembly 200. In oneconfiguration, where the surface 226 is planar, the discrete electrodes165 are distributed in a pattern that extends in at least twonon-parallel directions that are both parallel to a plane (e.g., X-Yplane) that is aligned parallel to the surface 226. Each of the discreteelectrodes 165 typically include a conductive rod 166 that is formedfrom a metal (e.g., copper, aluminum, nickel, silver, or alloys thereof)or other useful conductive material. The conductive rods 166 in someconfigurations may be cylindrical in shape, and thus have a diameter anda rod length which extends in a first direction (e.g., Z-direction inFIGS. 2A-2C2). In one example, the diameter of the conductive rods 166is between about 1 mm and about 15 mm. The conductive rods 166 in someconfigurations may be bar shaped, and thus have a non-circularcross-section and a rod length which extends in a first direction. Theconductive rods 166 are each coupled to a power distribution element 161at a connection point 167 by use of permanent or non-permanentconnection technique, such as by use of a welding or brazing process orby use of a set-screw, reusable electrical connector (e.g., banana plugtype) or other desirable coupling technique. The power distributionelement 161 includes a conductive structural element (e.g., metal plate)that is adapted to receive the RF power delivered from the RF sourceassembly 150 through one or more connecting elements 154, 155, anddistribute and deliver the received RF energy to each of the conductiverods 166. In some embodiments, the connecting elements 154 are coupledto the RF source assembly 150 through a connecting element 153 and a toppower distribution element 151 (e.g., metal plate). In some embodiments,the connecting element 155 is coupled to the RF source assembly 150through a connecting element 152. FIG. 2C1 is a bottom view of a portionof one configuration of the electrode assembly 160 as seen from thesection line shown in FIG. 2A. In one configuration, as shown in FIG.2C1, a power distribution element 161 disposed within the electrodeassembly 160 includes a conductive plate that is coupled to the centerconnecting element 155 at a center connection point 246 and connected tofour connecting elements 154 at four edge connection points 247. Thepower distribution element 161 includes a plurality of conductive legs248 that provide a conductive electrical path between one or more of theconnecting elements 154, 155 and/or between one or more of theconnecting elements 154, 155 and a plurality of the conductive rods 166.In one embodiment, as shown in FIG. 2C1, the power distribution element161 is configured to electrically connect all of the connecting elements154, 155 and all of the conductive rods 166 together so that RF powerdelivered through one or more of the connecting elements 154, 155 can bedistributed to each of the conductive rods 166 within the electrodeassembly 160.

In some embodiments, each of the conductive legs 248 includes aplurality of branch elements 248A that are configured to physically andelectrically connect the conductive rods 166 together and to connect theconductive rods 166 to the conductive legs 248. In some configurations,the branch elements 248A are symmetrically positioned relative to eachof the conductive legs 248. In some embodiments, the branch elements248A that are connected to different conductive legs 248 areelectrically isolated from each other by a gap 248B so as to control thepath length and electrical coupling between the connecting elements 154and the connecting element 155 and between each of the connectingelements 154. In some embodiments, gaps 248B formed between adjacentbranch elements 248A are all equal in size across the power distributionelement 161. While FIG. 2C1 illustrates a power distribution element 161that is radially symmetric and has four-fold symmetry this configurationis not intended to be limiting as to the scope of the disclosureprovided herein since other symmetric or non-symmetric configurations ofthe power distribution element 161 may be used. In one example, inconfigurations where the lid assembly 200 is circular in shape, it isbelieved that power distribution elements 161 that have a six-foldsymmetry (i.e., six conductive legs 248 that are coupled to sixconnecting elements 154 and a center connecting element 155) can have animproved and uniform power distribution over a two-fold or four-foldsymmetric configuration of a power distribution element 161. In otherexamples, power distribution element 161 can have a symmetry that isgreater than a two-fold, such as greater than six-fold symmetry. Inanother example, configurations where the lid assembly 200 is formed ina rectangular shape may require the power distribution element 161 tohave symmetry about two different directions (e.g., X and Y-axes). Thelid assembly 200 can be formed such that the surface 226 has arectangular shape, square shape, circular shape, oval shape or othersimilar shape, when viewed from the bottom side or top side (i.e.,viewed from +/−Z-direction). In some configurations, the lid assembly200 is configured to be symmetric about a central axis CA (FIG. 2A) thatpasses through a center point that is positioned at the surface 226, orother surfaces formed on or in the lid assembly 200, such as the lowersurface of the reference electrode element 225A. In one example, asillustrated in FIG. 2A, the central axis CA is positioned at the centerof a circular shaped lid assembly 200, when viewed from the+/−Z-direction, and oriented parallel to the +/−Z-direction andperpendicular to the X-Y plane.

FIG. 2C2 is a bottom view of a portion of an alternate configuration ofthe electrode assembly 160 as seen from the section line shown in FIG.2A. In the alternate configuration of the electrode assembly 160, analternate version of the power distribution element 161 is used in placeof the power distribution element 161 illustrated in FIG. 2C1. Thealternate version of the power distribution element 161 includes aconductive plate 261 that is coupled to the center connecting element155 at a center connection point 246 and connected to four connectingelements 154 at four edge connection points 247. The alternate versionof the power distribution element 161 is solid plate that includes aplurality of slots 262 formed through the conductive plate 261(Z-direction) that limit the current flow between regions of theconductive plate 261 and the connecting elements 154, 155 and/or betweenone or more of the connecting elements 154, 155 and a plurality of theconductive rods 166. The plurality of slots 262 can be oriented in aradial orientation, as shown in FIG. 2C2, and/or in a circular andconcentric configuration relative to the center of the conductive plate261 (not shown in FIG. 2C2) to allow a desired amount of electricalcommunication between different regions 265A-265D, or sectors, of theconductive plate 261. In one embodiment, the alternate version of thepower distribution element 161 is configured to electrically connect allof the connecting elements 154, 155 and all of the conductive rods 166together so that RF power delivered through one or more of theconnecting elements 154, 155 can be distributed to each of theconductive rods 166 within the electrode assembly 160. In someembodiments, the plurality of slots 262 formed through the conductiveplate 261 are configured to limit current flow between adjacent regionsof the conductive plate during processing.

Referring back to FIG. 1A, in some embodiments, the upper chamberassembly 20 further includes a shielding structure 140 that isconfigured to prevent the fields generated in the components thatdeliver RF power from the RF source assembly 150 to the processingregion 110 via the conductive rods 166 from affecting the uniformdelivery of RF power to the conductive rods 166. The shielding structure140 is generally an electrically conductive structure (e.g., aluminum)that is adapted to prevent the interaction of fields generated by eachof RF power delivery components with fields generated in adjacent RFpower delivery components and/or other adjacent grounded or ungroundedprocess chamber 100 components during processing. The shieldingstructure 140 includes feed conduits 145 that each separately enclose aconnecting element 152, 153, and are coupled to the RF source assembly150 at one end. The feed conduits 145 are coupled to a ground at theconnection point formed between the feed conduits 145 and an interfaceof the RF source assembly 150. The shielding structure 140 also includesa central feed conduit 141 that encloses the top power distributionelement 151 and is coupled to one end of a feed conduit 145 and eachdistributed feed conduit 142 at the other end. Each of the distributedfeed conduits 142 encloses at least a portion of one connecting element154. An end of each of the distributed feed conduits 142 are coupled tothe lid assembly 200, which allows the end of the distributed feedconduits 142 to be grounded. The shielding structure 140 also includes afeed conduit 143 that encloses at least a portion of the connectingelement 155. The feed conduit 143 is coupled to one end of a feedconduit 145 and a portion of each of the distributed feed conduits 142through a lower central feed conduit 146. It is believed that groundingthe opposing ends of the shielding structure 140 and separatelyenclosing each of the RF power delivery components within groundedconduit structures can significantly enhance the uniform delivery of RFpower to the processing region 110 through the one or more connectingelements 154, 155 and electrode assembly 160 components duringprocessing.

In some embodiments, the electrode assembly 160 further includes aplurality of electrode shields 168 that are adapted to physicallyseparate the conductive rods 166 from the processing region 110 of theprocess chamber. As illustrated in FIGS. 2A-2B, an electrode end 166A ofeach conductive rod 166 is inserted within a space (e.g., blind-hole)formed within an electrode shield 168. Physical separation of theconductive rods 166 from the processing region 110 by the electrodeshields 168 can prevent particle contamination of the process chamberand processed substrate(s) due to sputtering of the conductive rodmaterial due to a generated bias when RF power is delivered to theconductive rods 166 during plasma processing. The electrode shields 168may be formed from a dielectric or semiconducting material, such assapphire, silicon, silicon carbide, alumina, yttria, zirconia, a siliconoxide (SiO_(x)) containing material, such as quartz or fused silica, orcombinations thereof. In an alternate embodiment, each of the conductiverods 166 coated with a dielectric or semiconducting material, such assilicon or silicon dioxide using a silicon containing precursor (e.g.,silane) using an in-situ chemical vapor deposition (CVD) process step toform the electrode shields 168 and/or coat the processing region of theprocess chamber. In either case, at least a portion of the discreteelectrodes 165 and electrode shields 168 are disposed within the lidassembly 200 as illustrated in FIG. 2A, and a close-up view illustratedin FIG. 2B.

The lid assembly 200 includes a perforated faceplate 225 and a body 201which includes a lower plate 210, a support plate 212 and an upper plate214. The lower plate 210 of the body 201 is coupled to the perforatedfaceplate 225 by a bond layer 244. The bond layer 244 may be an organicadhesive in some embodiments. The upper plate 214 includes includethermal control conduits 250A and 250B formed therein. The upper plate214 may be made of a conductive material, such as aluminum, and iscoupled to lower plate 210 and support plate 212 by fasteners (notshown) such that a metal-to-metal contact is formed between the lowerplate 210, support plate 212 and upper plate 214. In some embodiments,the upper plate 214 includes insulating members 218 (FIG. 2B) that arepositioned around at least a portion of each of the conductive rods 166to reduce and/or minimize the capacitive coupling between the conductiverods 166 and the conductive material of the upper plate 214 duringplasma processing. In some embodiments, the lower plate 210, insulatingmembers 218 and/or support plate 212 are formed from a ceramic,semiconductor or dielectric material, such as silicon (Si), siliconcarbide (SiC), quartz, alumina (Al₂O₃), or aluminum nitride (AlN). Thebody 201 and the perforated faceplate 225 of the lid assembly 200 can becoupled to the chamber body 105 by fasteners (not shown). A seal 156,such as an elastomeric O-ring, may be disposed between the body 201 andthe chamber body 105 to seal the processing region 110 as well aselectrically insulate the body 201 from the chamber body 105.

In some embodiments, at least a portion of the electrode shields 168 aredisposed within and supported by one or more of the lid assembly 200components. As shown in FIGS. 2A-2B, the electrode shields 168 aredisposed between and sealed to the upper plate 214 and the lower plate210 by use of two O-rings 169. In this configuration, the electrodeshields 168 provide a vacuum to atmospheric pressure interface thatphysically isolates the conductive rods 166, which are disposed on theatmospheric pressure side of the lid assembly 200, from the vacuumenvironment maintained in the processing region 110 during processing.The insertion length 211 of the conductive rods 166 and the electrodeshields 168 into the processing region 110 can be controlled byselecting a lower plate 210 that has a desired thickness (e.g.,thickness in the Z-direction) or by selecting conductive rods 166 andthe electrode shields 168 that have a desired physical length. As isdiscussed further below, the insertion length 211 and/orelectrode-to-substrate spacing 213 can be adjusted to alter plasmaproperties over the surface of the substrate 112 and within theprocessing region 110. In one embodiment, in which both the conductiverods 166 and electrode shields 168 are used, the insertion length 211 ofeach of the ends of the electrode shields 168 (e.g., end of the discreteelectrodes 165) is between about −10 millimeters (mm) and about +20 mm,where a negative insertion length 211 is created when the electrode end166A of the conductive rods 166 and shield tip 168A is recessed withinthe hole in which a conductive rod 166 and electrode shield 168 residewithin the lower plate 210 of the lid assembly 200. In one embodiment,the insertion length 211 of the all of the electrode shields 168 isbetween about 0.1 millimeters (mm) and about 5 mm, such as between about1 mm and about 2 mm. In another embodiment, the insertion length 211 ofthe all of the electrode shields 168 in the discrete electrodes 165 isbetween about −10 mm and about −0.1 mm, such as between about −0.5 mmand about −2 mm. In one embodiment, the insertion length 211 of the allof the electrode shields 168 in the discrete electrodes 165 are all thesame length. In some embodiments, the spacing between the outer diameterof the electrode shield 168 and a hole 210A formed within the lowerplate 210 is minimized to prevent the possibility of plasma light-uptherein, as is discussed further below. In configurations where theelectrode shield 168 is not utilized the insertion length 211 ismeasured from the electrode end 166A to the surface 226.

While the conductive rods 166 and electrode shields 168 of the discreteelectrodes 165 are illustrated in FIGS. 2A-2C2 as being positioned in aperpendicular orientation to the surface 226 of the perforated faceplate225, this configuration is not intended to be limiting as to scope ofthe disclosure provided herein since the conductive rods 166 andelectrode shields 168 could be oriented at an angle relative to thesurface 226 or horizontal plane (e.g., X-Y plane), such as an angle 199as shown in FIG. 2B. In some configurations, the angle 199 may bebetween about 45° and about 90°, such as between about 85° and about90°.

The perforated faceplate 225 includes a plurality of openings 282 thatare coupled to a plurality of gas conduits 162 to provide a process gasto the processing region 110. In this embodiment, the gas conduits 162are formed through the lower plate 210, support plate 212 and upperplate 214 so as to provide the process gas to a distribution channel 283formed in the bond layer 244 and openings 282 formed in the perforatedfaceplate 225. The fluid source assembly 180 includes one or more gassources 243 that are configured to provide one or more process gases toone or more of the gas conduits 162 and the processing region 110. Insome embodiments, the process gas(es) provided from the one or more gassources 243 to the gas conduits 162 is controlled by use of conventionalmass flow controllers, valves and other conventional gas deliveryequipment that can be controlled by the system controller 50. Theprocess gases may be introduced into the processing region 110 from twoor more gas distribution zones formed in the perforated faceplate 225.The two or more gas distribution zones are typically divided radially,and may, for example, be used in combination with two or more of thezones illustrated in FIG. 2E (e.g., three zones 125A, 125B and 125C). Insome applications, two or more separated gas distribution networks areformed by use of separate gas conduits 162 when incompatibilities existbetween process gases or when mixing in processing region 110 isrequired. In some embodiments, the one or more gas sources 243 can becontrolled so as to provide localized gas distribution control acrossdifferent regions of the perforated faceplate 225, such as between thecenter region and the edge region. The localized gas control may includethe adjustment of the gas flow ratios of the various process gases, suchas polymerizing to non-polymerizing chemistries, oxidizing tonon-oxidizing chemistries, differing ratios of deposition precursorgases, and/or inert to reactive chemistry ratios.

The perforated faceplate 225 may be made of a silicon containingmaterial, such as a silicon carbide (SiC) disk or a silicon waferutilized in electronic device manufacturing processes. In oneembodiment, the perforated faceplate 225 may include a silicon carbide(SiC) material that has a silicon dioxide (SiO₂), silicon nitride(Si₃N₄), silicon (Si), aluminum nitride (AlN) or graphite plate that ispositioned thereon, such that the silicon carbide (SiC) material ispositioned such that it faces away from the surface 226, or is on asurface that is opposite to the surface 226. In another embodiment, theperforated faceplate 225 may be formed from a material such as sapphire,silicon, alumina, yttria, zirconia, aluminum nitride or silicon oxide(SiO_(x)). The perforated faceplate 225 may be any size and include anysuitable surface area. However, in one embodiment, the perforatedfaceplate 225 is a 450 millimeter (in diameter) silicon wafer. Thesilicon material of the perforated faceplate 225 may be doped orun-doped to provide enhanced conductive or dielectric properties. Theperforated faceplate 225 may optionally include a reference electrodeelement 225A that includes a conductive layer, a distributed conductiveregion, conductive sheet or conductive plate that is used as a referenceelectrode for the RF power delivered to the plurality of discreteelectrodes 165. In some embodiments, the reference electrode element225A includes a metallic layer (e.g., Al, Ni, Cu) that is formed on asurface of the perforated faceplate 225 by use of conventionaldeposition or doping process. In some embodiments, the referenceelectrode element 225A includes a doped region of a dielectric orsemiconducting material that is formed on a surface of the perforatedfaceplate 225. In some embodiments, the reference electrode element 225Ais disposed on a surface of the perforated faceplate 225 that is notdirectly exposed to the processing region 110. In one embodiment, thereference electrode element 225A includes a lower surface that isoriented substantially parallel to an adjacently positioned surface ofthe substrate 112 (e.g., top surface of the substrate). As illustratedin FIG. 2A, the lower surface may extend in directions that are parallelto the X-Y plane and have opposing outside edges that are at least aslarge as the largest dimension of the substrate 112 (e.g., ≥300 mm for a300 mm sized substrate). In one configuration, the lower surface ofreference electrode element 225A is planar as illustrated in FIG. 2A, orhas a curved shape (e.g., convex shape or concave shape relative to theX-Y plane). However, in configurations where the lid assembly 200 onlycovers a portion of the substrate surface, such as the “wedge shaped”configuration illustrated in FIG. 7B, the lower surface of the referenceelectrode element 225A is formed such that reference electrode element225A has a surface area that is smaller than the surface area of theupper surface of the substrate 112. In this case, the referenceelectrode element 225A can have a non-circular or circular shape in aplan view. In some configurations as discussed further below inreference to FIG. 7B, the reference electrode element 225A can have alength dimension that is at least as large as the diameter of asubstrate 112, but have a lateral dimension in the X-Y plane (e.g.,width or angular shaped sector dimension) that is less than the diameterof a substrate 112. In some alternate configurations where the substrateis rotated about the substrate's center during plasma processing, thereference electrode element 225A can be configured to have a length thatextends in a radial direction from the center of the round substratepast the outer edge of the substrate and have a circumferential extentin a plan view that is defined by an angle (e.g., acute angle, obtuseangle).

In one embodiment, the reference electrode element 225A is coupleddirectly to an RF ground at one or more locations. However, in someembodiments, as is further discussed below (see FIG. 3A), the referenceelectrode element 225A is coupled to an RF ground through an impedancecontrolling device, such as an RF match. In some embodiments, the RFground connections made to the reference electrode element 225A aresymmetrically disposed about an axis of symmetry or other symmetricalfeature. The number of RF ground connections may be at least equal tothe number of connecting elements 154 used in the upper chamber assembly20.

In an alternate configuration of the perforated faceplate 225, theperforated faceplate 225 does not include the reference electrodeelement 225A and thus electrically floats relative to the applied RFpower delivered to the actively biased conductive rods 166. In thisconfiguration, a portion of the conductive rods 166 are directly orselectively connected to a ground, and thus act as reference electrodefor the other conductive rods 166 that are actively biased by the RFsource assembly 150 components. In one configuration, half of theconductive rods 166 are actively biased by the RF source assembly 150and the other half are grounded during processing, wherein at least oneof the nearest neighbors of an actively biased conductive rod 166 is agrounded conductive rod 166.

The openings 282 formed in the perforated faceplate 225 may be formedusing suitable hole forming techniques such as etching or laserdrilling. In one embodiment, the openings 282 are formed by athrough-silicon-via (TSV) process. In one embodiment, the diameter ofeach of the openings 282 is about 50 microns (μm) to about 64 μm. Inconfigurations where the openings 282 do not have a circularcross-sectional shape it is desirable to keep the maximumcross-sectional dimension of the opening to a size less than about 50microns (μm) to about 64 μm. The openings 282 may be numerous inrelation to the surface area of the perforated faceplate 225 (i.e.,dense) to maximize flow conductance and/or minimize pressure in thedistribution channels 283. As illustrated in FIGS. 2A-2B, the openings282 are positioned in an array or pattern across the surface 226 of theperforated plate 225. The array or pattern is typically configured tointerleave with the discrete electrodes 165 and to provide a desirablegas flow pattern across the surface 226 of the perforated faceplate 225,and thus within the processing region 110. One or more of the sizes ofthe openings 282 and the density of the openings 282 are adjusted toreduce the possibility of plasma light-up in the distribution channels283 or other portions of the body 201. The need to suppress plasmalight-up in the openings 282, distribution channels 283 or otherportions of the body 201 is increasingly important in configurationswhere the reference electrode element 225A is positioned in closeproximity to the discrete electrodes 165. Utilizing a silicon wafer forthe perforated faceplate 225 provides a replaceable consumable elementof the lid assembly 200. For example, as plasma may erode surfaces ofthe perforated faceplate 225 over time. When eroded, the perforatedfaceplate 225 may be decoupled from the lower plate 210 and a newperforated faceplate 225 may be bonded thereto.

FIGS. 2D-2F are bottom views of the lid assembly 200 that illustratediffering patterns of discrete electrodes 165 which can be used togenerate a plasma having desirable plasma properties during a plasmaprocessing. It is noted that the openings 282 have been omitted from thesurface of the perforated faceplates 225 illustrated in FIGS. 2D-2F forclarity of discussion purposes. FIG. 2D illustrates a lid assembly 200configuration that has a non-uniform radial distribution of discreteelectrodes 165 across the surface 226 of the perforated faceplate 225.FIG. 2E illustrates a lid assembly 200 configuration that has threezones 125A, 125B and 125C that each have a differing radial distributionof discrete electrodes 165 formed therein. In some configurations, eachof the discrete electrodes 165 in each of the different zones can beseparately biased to provide a different plasma density therein. In oneexample, each of the discrete electrodes 165 in the first zone 125A arecoupled to a first power distribution element, each of the discreteelectrodes 165 in the second zone 125B are coupled to a second powerdistribution element and each of the discrete electrodes 165 in thethird zone 125C are coupled to a third power distribution element,wherein each of the first, second and third power distribution elementscan be biased in unison or separately by the components found in the RFsource assembly 150. FIG. 2F illustrates a lid assembly 200configuration that has a uniform distribution of discrete electrodes 165across the X-Y plane and the surface 226 of the perforated faceplate225. The various configurations of discrete electrodes 165 shown inFIGS. 2D-2F are intended to illustrate just a few examples of arrays ofdiscrete electrodes 165 that are distributed in a pattern that isaligned parallel to a plane (i.e., X-Y plane). As shown, the illustratedpatterns include arrays of discrete electrodes 165 that are distributedin at least two non-parallel directions (e.g., X and Y directions).

FIG. 2G is a bottom view of a portion of a lid assembly 200 thatschematically illustrates a pattern of discrete electrodes 165, aninterspersed pattern of gas delivery openings 282 and a portion of areference electrode element 225A. The portion of the reference electrodeelement 225A illustrated in FIG. 2G is shown without any interveningmaterials (e.g., non-conductive part of the perforated faceplate 225)for ease and clarity of discussion.

FIG. 2H is a bottom view of a portion of a lid assembly 200 thatincludes a partial section view of a discrete electrode 165 and a bottomview of faceplate 225. As illustrated in FIG. 2H, the discrete electrode165 is disposed through a portion of faceplate 225, and includes aconductive rod 166 and an electrode shield 168, as discussed above. Insome embodiments, a shield gap 278 is formed between the conductive rod166 and the electrode shield 168. It is generally desirable to minimizethe size of the shield gap 278 to improve the capacitive coupling of theconductive rods 166 to the processing region 110 during processing.However, in some configurations the shield gap 278 may be designed to bebetween 0.01 mm and 1 mm. Additionally, a vacuum gap 276 is formedbetween the surface of a discrete electrode 165 and an adjacent surfaceof the perforated faceplate 225 and lower plate 210. The vacuum gap 276is a non-material containing region (e.g., vacuum containing region)that is formed between the outer edge of each discrete electrode 165(e.g., outer surface of the electrode shield 168) and the adjacentlypositioned surface(s) of the perforated faceplate 225 and lower plate210. In one example, the adjacent surfaces can include a through holethat has an inner edge 229 that is spaced a distance 279 equal to thevacuum gap 276 from the outer surface of the discrete electrodes 165.The vacuum gap 276 is generally sized so that a plasma will not beformed in the space formed therebetween during processing, and may bebetween 0.1 mm and 1 mm in size, such as between about 0.1 and about0.25 mm.

As illustrated in FIG. 2G, the discrete electrodes 165 are disposed indesired pattern across the X-Y plane that is, for example, parallel tosurface 226 of the lid assembly 200. The reference electrode element225A (i.e., cross-hatched region) is also disposed around and in-betweeneach of the discrete electrodes 165 arranged in the desired pattern toprovide a symmetric and reliable ground path for the RF power providedto each of the discrete electrodes 165 by the RF source assembly 150. Asshown in FIGS. 2G and 2H, at least a portion of the reference electrodeelement 225A surrounds each of the discrete electrodes 165. The totalarea associated with the exposed tip surface area of each discreteelectrode 165 exposed to the processing region can be defined as theelectrode surface area A1 and the cross-hatched region of the referenceelectrode element 225A can be defined as the total reference electrodesurface area A2. A symmetric and reliable ground path with a determinedratio between the discrete electrode surface area A1 and referenceelectrode surface area A2 can be important for controlling plasmauniformity, plasma density or plasma ion energy when used in processchamber configurations that have a symmetrically configured processingregion 110 and also used in process chamber configurations that havenon-symmetrically configured processing region 110 defining components(e.g., chamber liner 107) and/or chamber walls.

An electrode gap 287 is formed between each discrete electrode 165 andthe reference electrode element 225A. The electrode gap 287 is definedby the distance 286 formed between an edge 288 of the referenceelectrode element 225A and a portion of a discrete electrode 165. Thespace, or distance 286, is defined by the smallest distance createdbetween a portion of a discrete electrode 165 and the edge 288 of thereference electrode element 225A. In some configurations, an interveningsemiconducting and/or dielectric material and vacuum containing region(e.g., vacuum gap 276) may be disposed within the electrode gap 287.Referring to FIGS. 2G and 2H, in some embodiments in which an electrodeshield 168 is utilized, the electrode gap 287 is formed between anoutside edge of the electrode shield 168 of the discrete electrode 165and the edge 288, or the electrode gap 287 may be formed from the shieldtip 168A (FIG. 2B) of the electrode shield 168 and the edge 288,depending on the insertion length 211 of the discrete electrodes 165within the lid assembly 200. As shown in FIG. 2H, the electrode gap 287has a distance 286 formed between the outside edge of the electrodeshield 168 and the edge 288 that is different from the distance 279 ofthe vacuum gap 276 formed between the edge 299 of the faceplate 225 andthe electrode shield 168. In an alternate configuration, the distance286 of the electrode gap 287 may be the same as the distance 279 of thevacuum gap 276 between the discrete electrode 165 and the edge 299 ofthe faceplate 225 (not shown). In some embodiments, the distance 286 isbetween about 0.5 mm and about 10 mm, such as between about 1 mm andabout 5 mm. In one example, the distance 286 provided by the electrodegap 287 is set at about 3 mm when a plasma process is performed in theprocess chamber is commonly run at pressures near 10 Torr, and is set atabout 10 mm when the plasma process is commonly run at pressures near 1Torr. While the pattern of discrete electrodes 165 and interspersedpattern of gas delivery openings 282 are illustrated in FIG. 2G in asquare or a rectangular pattern this configuration is not intended to belimiting as to the scope of the disclosure provided herein since anyother desirable pattern of discrete electrodes 165 and/or openings 282may be used (e.g., radial pattern or hexagonal pattern).

FIG. 2I is a schematic side cross-sectional view of a portion of thediscrete electrodes 165 illustrated in FIG. 2B with portions of lidassembly 200 removed for clarity. As illustrated in FIG. 2I, thediscrete electrodes 165 each include a conductive rod 166 that isattached to the power distribution element 161. The conductive rod 166is inserted into electrode shield 168 which surrounds a lower portion ofconductive rod 166 and is designed to physically separate the conductiverod 166 from the processing region 110 (FIGS. 1A and 2A) of a processchamber 100. The conductive rod 166 and the electrode shield 168 arepositioned through openings in the reference electrode element 225A sothat portions of the conductive rod and/or electrode shields are in aposition to influence a plasma formed in the processing region 110. Asshown in FIG. 2I, the outer surface portion of the electrode shield tip168A that is exposed to the processing region of the processing chamberand is below the reference electrode element 225A has a surface area A1and the reference electrode element 225A has a surface area of A2 whichfaces the processing region. It has been found that the ratio of the sumof the surface areas A1 of the discrete electrodes 165 to the referenceelectrode element surface area A2 can influence the plasma density,plasma uniformity or plasma ion energy during processing. In operation,there are a number of ways to change the ratio between areas A1 and A2.In one example, the area A1 can be controlled by determining theinsertion length 211 (FIG. 2B) of the portion of the discrete electrodethat is positioned through the hole in the reference electrode element225A and exposed to the processing region. The greater the portion ofeach of the discrete electrodes 165 that are exposed to the processingregion, the greater the area A1 relative to A2. Controlling theinsertion length 211 (FIG. 2B) of each of the discrete electrodes 165exposed to the processing region can be achieved by selecting a lowerplate 210 that has a desired thickness (e.g., thickness in theZ-direction) or by selecting conductive rods and electrode shields thathave a desired length. Also, the surface area A2 of the referenceelectrode element can be adjusted and configured to achieve a desiredratio between areas A1 and A2.

FIG. 2J is a cross-sectional view of another embodiment of a discreteelectrode 165 that can be used to control the area ratio between area A1and area A2. In one configuration, the discrete electrode 165 includeselectrode shield 168 that has a laterally configured tip portion 273that is wider than the configuration of the electrode shield tip 168Aportion of the electrode shield 168 shown in FIG. 2I. The electrodeshield 168 includes sidewalls 272, flattened bottom tip portion 273, andinterior portion 274 having interior sidewall 276 and interior bottomsurface 275. Conductive rod 166 is attached to, or is formed with, aconductive tip 290 that has a desired shape and size (e.g., surfacearea). The conductive tip 290 is generally configured to generate adesired local plasma uniformity and plasma density within the processingregion 110 by desirably distributing the generated electric fieldscreated during processing due to its shape and its position within thediscrete electrode 165 and position relative to the reference electrodeelement 225A. In one configuration, the conductive tip 290 has a greaterlateral area (i.e., X-Y plane illustrated in FIG. 2H) than theconductive rod 166. The conductive tip 290 may be formed of a metal(e.g., copper, aluminum, nickel, silver, titanium or alloys thereof) orother useful conductive material. In one embodiment, the conductive tip290 may be formed from the same conductive material as the conductiverod 166. In one embodiment, the conductive tip 290 is formed from aconductive material different from the conductive rod 166.

In some embodiments, to assure that the conductive rods 166 and theconductive tips 290 have a consistent relationship to the electrodeshield 168 and lid assembly 200, a spring assembly 280 is provided toapply pressure to the conductive rod 166 and the conductive tip 290 sothat the conductive tip 290 is at least in contact with the interiorbottom surface 275 of tip portion 273 of the electrode shield 168. Insome embodiments, the electrode shield 168 includes an upper shieldportion 271 that rests on a surface of the lower plate 210 to reliablyfix the position the interior bottom surface 275 relative to thereference electrode element 225A. In one configuration, as shown in FIG.2B, the upper shield portion 271 of an electrode shield rests on anO-ring 169 that rests on a surface of the lower plate 210. Thus, theconfiguration of the spring assembly 280, conductive rod 166, conductivetip 290, electrode shield 168 and position of the supporting surface ofthe lower plate 210 is used to provide a consistent orientation andposition (e.g., Z direction) of the conductive tip 290 relative to thereference electrode element 225A and the processing region 110 of theprocessing chamber.

FIG. 2K is a close up illustration of the conductive tip 290 shown inFIG. 2J. Conductive rod 166 fits within receptacle 294 of electrodeconductive tip 290. Lower curved regions 292 provide an exposed edgeregion that has a “curved edge” or shaped edge 295 that joins the lowersurface 291 to the sidewall 293. The lower surface 291 combined with theshaped edge 295 provides a desirable electrode shape that includes awide flat contact surface at the conductive tip 290. The flat contactsurface can be used to maintain a solid and uniform contact across theflat interior bottom surface 275 of electrode shield 168, therebyassuring consistent lengths of the conductive rods 166 and conductivetips 290 distributed across the lid assembly 200 that have the same orsimilar style conductive tips 290.

FIG. 2L is a close-up illustration of an alternate embodiment ofconductive tip 290. In this embodiment, conductive tip 290 has a lowersurface 291 that has a non-flat or curved shape that is connected tosidewall 293 of the conductive tip 290. The curved shape of the lowersurface 291 could be a hemispherical shape, a conical shape (not shown)or any other curved profile. The curved shape of lower surface 291 canprovide a desired field shape when RF biased and/or a consistent pointof contact with the interior bottom surface 275 of electrode shield 168(e.g., avoiding parallelism issues when mating flat surfaces), therebyassuring consistent lengths of the conductive rod 166 and conductivetips 290 across the lid assembly 200 when using the same styleconductive tips 290.

FIG. 2M is a close-up illustration of another alternate embodiment ofconductive tip 290 as shown in FIG. 2J. In this embodiment conductivetip 290 has t-shaped configuration that has a lower surface 291, ashaped edge 295, a lower sidewall 296, a shaped upper region 297 and ajoining region 298. The joining region 298 joins the shaped upper region297 to the upper sidewall 293. The lower surface 291 combined with theshaped edge 295 provides a contact surface that can allow the conductivetip 290 to maintain solid and uniform contact across the flat interiorbottom surface 275 of electrode shield 168 thereby assuring consistentlengths of the conductive rod 166 and conductive tips 290 across the lidassembly 200 when using the same style conductive tips. While not shownin FIG. 2M, in some embodiments, the lower surface 291 can have a curvedshape (e.g., convex or concave shape) to provide a desired field shapewhen RF biased and/or a consistent point or line contact with theinterior bottom surface 275 of electrode shield 168.

FIG. 2N illustrates a bottom view of an alternate embodiment of therelationship of a reference electrode element and the array of discreteelectrodes shown in FIG. 2G. FIG. 2N depicts an array of discreteelectrodes 165 where the relationship of the total exposed surface areaof the discrete electrodes 165, or sum of the electrode surface areas A1of the discrete electrodes 165, is approximately the same as surfacearea A2 of the reference electrode element 225A. The areas A1 and A2 donot include the electrode gap 287 formed between the edge of thediscrete electrode 165 and the edge 288 of the reference electrodeelement 225A. The distance 286 across the electrode gap 287 surroundingthe discrete electrodes 165 can be adjusted to control a property of aformed plasma and/or adjust the area A2 of the reference electrodeelement 225A. It has been found that there is an increased consistencyof the plasma density and plasma uniformity when using configurationsthat have a total area of the discrete electrodes 165, or sum of theareas A1 of the discrete electrodes 165, is the same as the area A2attributed to the lateral surface area (e.g., parallel to X-Y planeillustrated in FIGS. 2A and 2N) of reference electrode element 225Afacing the processing region. In one example, the ratio of the sum ofthe electrode surface areas A1 to the surface area A2, which faces theprocessing region, is between a ratio of 0.8:1 and 1.2:1. In anotherexample, the ratio of the sum of the surface areas A1 to the surfacearea A2, which faces the processing region, is between a ratio of 0.9:1and 1.1:1.

Referring back to FIG. 2A, in some embodiments, the thermal controlconduits 250A and 250B are operably coupled to a temperature controlsystem (not shown). The temperature control system includes atemperature controller (not shown) that is in communication with thesystem controller 50. The system controller 50 is generally designed tofacilitate the control and automation of the process chamber 100 and maycommunicate with the various sensors, actuators, and other equipmentassociated with the process chamber 100. The system controller 50typically includes a central processing unit (CPU) (not shown), memory(not shown), and support circuits (or I/O) (not shown). The CPU may beone of any form of computer processors that are used in industrialsettings for controlling various system functions, substrate movement,chamber processes, and control support hardware (e.g., sensors, internaland external robots, motors, gas flow control, etc.), and monitor theprocesses performed in the system (e.g., RF power measurements, chamberprocess time, I/O signals, etc.). The memory is connected to the CPU,and may be one or more of a readily available memory, such as randomaccess memory (RAM), read only memory (ROM), floppy disk, hard disk, orany other form of digital storage, local or remote. Softwareinstructions and data can be coded and stored within the memory forinstructing the CPU. The support circuits are also connected to the CPUfor supporting the processor in a conventional manner. The supportcircuits may include cache, power supplies, clock circuits, input/outputcircuitry, subsystems, and the like. A program (or computerinstructions) readable by the system controller 50 determines whichtasks are performable on a substrate in the process chamber 100.Preferably, the program is software readable by the system controller 50that includes code to perform tasks relating to monitoring, executionand control of the movement, support, and/or positioning of a substratealong with the various process recipe tasks and various chamber processrecipe operations being performed in the process chamber 100.

The temperature control system may include temperature sensors that arein communication with the temperature controller. The temperaturesensors may be positioned within the body 201 to monitor temperature ofthe body 201 of the lid assembly 200. In some embodiments, the chamberbody 105 includes a temperature control conduit that is coupled to thetemperature controller. The temperature controller may include servocontrollers that control electrical power to the resistive heater andflow control of fluids to the thermal control conduits 250A. Inoperation, a set-point temperature for the lid assembly 200 may beprovided by the system controller 50 to the temperature controller basedon feedback from one or more of the temperature sensors. Embodiments ofthe temperature control system can be used to provide uniformtemperature of the lid assembly 200 during cycling between the plasma-onstate and the plasma-off state. Maintenance of the process set-pointtemperature may result in more stable process results within a singlesubstrate process as well as substrate to substrate processing. In thismanner, temperature control of the lid assembly 200, and processingtemperature, is reliably controlled. Embodiments of the temperaturecontrol system as described herein may be utilized to maintain aset-point temperature of about 120 degrees Celsius to about 160 degreesCelsius.

Referring back to FIGS. 1A-1B, the lower chamber assembly 30 includes achamber body 105 and a support assembly 115. The support assembly 115may include an electrode 464 that can be biased by use of a supportingRF source assembly 460. The supporting RF source assembly 460 includesan RF power supply 461 and RF match 462 that are configured to provideRF power to the electrode 464 a frequency between about 50 kHz and 200MHz, such as between about 13.56 MHz and about 162 MHz, or even betweenabout 50 MHz and about 162 MHz. The supporting RF source assembly 460may also include a switching device 469 that is disposed between theelectrode 464 and the RF power supply 461, such as between the electrode464 and the RF match 462. The switching device 469 may include an RFcoaxial vacuum relay that has high impedance when in its open state anda low impedance in its closed state, as discussed further below. Theelectrode 464 can thus be used in conjunction with the discreteelectrodes 165 to form a plasma in the processing region 110. The RFpower supplied to the electrode 464 may be adjusted, along with theposition of the substrate 112 relative to the discrete electrodes 165and/or the RF power provided to the discrete electrodes 165, to controlthe interaction of the formed plasma (e.g., amount of radical and/or ioninteraction) with the exposed surfaces of the substrate 112. The supportassembly 115 may be a vacuum chuck, an electrostatic chuck, or othertype of substrate support that may be made of a thermally conductivematerial, such as aluminum or aluminum nitride.

The chamber body 105 includes a chamber liner 107 that is configured toseparate the processing region 110 from the lower chamber region 430.The chamber body 105 includes a plurality of chamber side walls 405, andchamber floor 410 that can be formed from one or more process-compatiblematerials, such as aluminum, anodized aluminum, nickel plated aluminum,nickel plated aluminum 6061-T6, stainless steel, as well as combinationsand alloys thereof, for example. The plurality of chamber side walls 405and chamber floor 410 are configured to support one more of thecomponents contained within the upper chamber assembly 20 and allow adesirable pressure to be maintained within the processing region 110,lower chamber region 430 and evacuation region 411 by use of a pump 440.In one example, the pump 440 includes a turbo pump and/or mechanicalpump that is able to generate a vacuum pressure within processing region110, lower chamber region 430 and evacuation region 411. In oneprocessing example, a vacuum pressure is maintained within processingregion 110, during plasma processing of a substrate 112, to a pressurebetween about 10 mTorr and 10 Torr, such as between about 100 mTorr and10 Torr.

The chamber body 105 also includes a load port (not shown) formed in oneof the side walls 405. Then load port is selectively opened and closedby a slit valve (not shown) to allow access to the interior of thechamber body 105 by a substrate handling robot (not shown). A substrate112 can be transferred in and out of the process chamber 100 through theload port to an adjacent transfer chamber (not shown) on which theprocess chamber 100 is disposed and/or load-lock chamber, or anotherchamber within a cluster tool in which the process chamber 100 resides.The support assembly 115 may be movable relative to the chamber body105. A substrate 112 may be disposed on the upper surface 130 of thesupport assembly 115 for processing. The support assembly 115 may be ina position adjacent to the load port for substrate transfer. The supportassembly 115 may also move to a position in proximity to the lowersurface 126 of the lid assembly 200 for processing. The support assembly115 may also be rotatable relative to the chamber body 105. Lift pins(not shown) may also be used to space the substrate 112 away from theupper surface 130 of the support assembly 115 to enable exchange withthe substrate handling robot during substrate transfer.

As shown in FIG. 1A, the side walls 405 and the chamber floor 410enclose an evacuation region 411. The vacuum pump 440 is disposed in avacuum pump opening 410 a in the chamber floor 410 and is centeredrelative to the axis of symmetry of the side walls 405. A containmentwall 415 coaxial with the support assembly 115 and a flexible bellows417 extending between the pedestal 120 and the containment wall 415enclose the support assembly 115 in an internal central space 419. Thecentral space 419 is isolated from the volume evacuated by the vacuumpump 440, including the evacuation region 411 and the processing region110. Referring to FIG. 1B, there are three hollow radial struts 420defining radial access passages 421 spaced at 120 degree intervalsextending through the chamber body side wall 405 and providing access tothe central space 419. Three axial exhaust passages 422 are definedbetween the three radial struts 420. Different utilities may be providedthrough different ones of the radial access passages 421, including theRF power cable or rigid RF transmission line 132 connected to theelectrode 464, heater voltage supply lines connected to heater elementsin the support assembly 115, an electrostatic chucking voltage supplyline connected to the electrode 464, coolant supply lines and heliumsupply lines for backside helium gas channels in the workpiece supportsurface 121, for example. A workpiece support lift actuator 450 is fixedwith respect to the chamber body and moves the support assembly 115vertically (e.g., Z-direction) by use of a mechanical actuator (notshown). The workpiece support lift actuator 450 can thus be used tocontrol the electrode-to-substrate spacing 213 (FIG. 2B) by use ofcommands received from the system controller 50. Varying this distancevaries the distribution of plasma ion density within the formed plasma111. Movement of the lift actuator may be used to improve uniformity ofdistribution of process (e.g., etch) rate across the surface of thesubstrate 112. Varying this distance may also be used to vary the ratioof plasma ion or electron density with respect to plasma radical densityat the workpiece. In some embodiments, it is desirable to adjust theelectrode-to-substrate spacing 213 during different portions of a plasmaprocessing recipe performed on a substrate so that the amount ofexposure of the surface of the substrate to ions and/or radicals formedin the plasma can be adjusted. In one example, it is desirable toposition the surface of the substrate closer to the discrete electrodes165 during a first process step to allow the substrate to be exposed toa first amount of ions generated in the plasma, and then position thesurface of the substrate a distance further away from the discreteelectrodes 165 during a second process step to allow the substrate to beexposed to a second amount of ions generated in the plasma. In thisexample the second amount of ions that the substrate surface is exposedto will be less than the first amount ions the substrate surface isexposed to during the first process step. In another example, thespacing between the substrate and the discrete electrodes 165 isreversed from the previous example by switching the order of theprocessing steps during processing in order to alter the exposure of thesubstrate surface to the amount of generated ions. The lift actuator 450may be controlled by the user through system controller 50, for example.

The axially centered exhaust assembly including the vacuum pump opening410 a and the axial exhaust passages 422 avoids asymmetries or skew inprocessing distribution across the substrate 112. The lower annular grid107B masks the processing region 110 from the discontinuities or effectsof the radial struts 420. The combination of the axially centeredexhaust assembly with the symmetrical distribution of RF current flowbelow the ground plate 184 minimize skew effects throughout theprocessing region 110, and enhance process uniformity in the processingregion 110.

In one embodiment, the upper chamber assembly 20 includes a magnetassembly that includes an electromagnet 176 that is powered by a magnetsource 177. The magnet assembly may be an axisymmetric or cusp typemagnet system that creates a B-field with peak fields at the edge or inthe center of the process chamber. Alternately, the magnet assembly mayinclude an “X-Y” coil assembly (e.g., two or more coils) that provides amagnetic field that can be directed across the surface of the substratein an arbitrary direction parallel to the surface of the substrate byuse of a combination of currents provided through the desirably orientedcoil(s) found in the “X-Y” coil assembly. The ability to alter thegenerated magnetic field can be useful to compensate for an asymmetry inthe plasma formed by the components found in the electrode assembly 160.The ability to alter the generated magnetic field can also be useful tocorrect for any asymmetry in a property of the substrate (e.g., existingthickness non-uniformity) that is to be processed in the processchamber, or to deliberately create an asymmetry in the process resultsperformed on the substrate in the process chamber in anticipation of askew in the process results found in a subsequent process step performedon the substrate. The magnet assembly may be used to tune the plasmaproperties so as to alter one or more process variables, such as etchrate or deposition rate. For example, at high RF frequencies, such as162 MHz the magnets may be utilized to reduce a peak in the plasmadensity found near the center of the substrate 112. In some embodiments,lower RF frequencies (e.g., about <60 MHz) may not need magnets to tunethe generated plasma.

RF Power Delivery Configuration Examples

FIG. 3A is a cross-sectional view of the main RF power delivery elementsdisposed within the electrode assembly 160 of the lid assembly,according to an embodiment of the disclosure provided herein. Theelectrode assembly 160 includes the connecting elements 154 and a centerconnecting element 155 that are coupled to the conductive rods 166through the power distribution element 161. The conductive rods 166 areconfigured to be biased relative to a reference electrode, such as thereference electrode element 225A or process chamber walls (not shown) byuse of the RF power generation components found in the RF sourceassembly 150. During processing, an RF current “A” is provided from a RFsource that is coupled to the connecting element(s) 155 and a RF current“B” is provided from a RF source that is coupled to the connectingelements 154. As is further discussed below, the RF source providingpower to the connecting elements 154 and 155 may be the same RF sourceor different RF sources. By controlling the characteristics of the RFpower delivered through each of the connecting elements 154, 155 and byuse of the structural aspects of the RF power conducting elements, suchas the power distribution element 161 and conductive rods 166, theuniformity of the RF power that is provided to the processing region 110and thus generated plasma 111 can be controlled. In some embodiments,the physical characteristics of the RF power distribution components inthe electrode assembly 160 and/or the position where the connectingelements 154, 155 contact the power distribution element 161 areconfigured so that the RF power provided by the RF source(s) has adesired generated wave pattern based on the interference created betweenthe RF power provided to the different power delivery elements withinthe electrode assembly. In some embodiments, the electricalcharacteristics of the RF power provided to the connecting elements 154,155 and power distribution element 161 (e.g., phase angle, frequency,power) are adjusted so that the RF power provided by the RF source(s) isable to achieve a desired wave pattern and forward RF power signal basedon the impedance of the driven components, load created by the plasmaand the interference created between the RF power provided separately todifferent parts of the power delivery elements found within theelectrode assembly.

FIG. 3B is a cross-sectional view of another configuration of the mainRF power delivery elements disposed within the electrode assembly 160 ofthe lid assembly. The configuration illustrated in FIG. 3B differs fromthe configuration illustrated in FIG. 3A in that the connection point363 of a connecting element, such as connecting element 155 shown inFIG. 3A, can be adjusted during manufacturing of the process chamber 100or while the process chamber is installed in the field by use of aconnection assembly 330 that couples an end of a connecting element to aportion of the power distribution element 161. In one embodiment, theconnection assembly 330 includes a distribution plate 331 that includesa plurality of connecting features 332 that are each configured toaccept an end of a conductive connecting element 341 that is coupled toa portion of the power distribution element 161 at its opposing end. Insome configurations it is desirable to position one or more of theconductive connecting elements 341 in a connecting feature 332 so thatthe one or more conductive connecting elements 341 are a distance 335from a symmetric position of the power distribution element 161 (e.g.,center point of the power distribution element). The distance 335, orspacing of the features 332, may be configured to minimizenon-uniformity for a particular load condition and driven RF frequency.The ability to adjust the physical position of one or more connectionpoints made between a connecting element 154, 155 and the powerdistribution element 161 can be used to compensate for and/or create adesired asymmetry in the plasma formed in the processing region 110 byaltering the generated wave pattern formed in the power distributionelement 161.

The plurality of discrete electrodes 165, the power distribution element161, and the reference electrode 225B are depicted as a loadedtransmission line system 190 in FIGS. 4A-4B, 5A-5B, 6A-6B and 7A, whichare further described below. The reference electrode 225B may includethe reference electrode element 225A and/or grounded process chamberwalls. In another embodiment, the reference electrode 225B is formedfrom a portion of the plurality of discrete electrodes that areseparately grounded versus the reference electrode element 225A, aspreviously discussed.

FIG. 4A is a schematic depicting an embodiment of the RF source assembly150 for driving the plurality of discrete electrodes 165. The RFdelivery assembly 150 includes an RF generator 351, a matching network355, and connecting elements 154, 155. The power distribution element161, the plurality of discrete electrodes 165, and the reference groundof FIG. 3A are depicted as a transmission line system 190 loaded with aplurality of impedances 365 that schematically represent the impedancecreated when a plasma is generated in the processing region 110 by thedelivery of RF power to the discrete electrodes 165. The plurality ofimpedances 365 are generally complex impedances(Z(f)=R(f)+j(X_(L)(f)+X_(C)(f)) that vary as the amount of RF power at adriven frequency and phase are adjusted or vary during the formation ofa plasma within the processing region 110. The impedances 365 typicallyinclude a resistive component R, an inductive component X_(L) and acapacitive component X_(C). A junction 361 connects the output of thematching network 355 to the power distribution element 161 using theconnecting elements 154, 155. For simplicity of discussion, in thisexample, the formed electrical circuit includes two connecting elements154 and one connecting element 155, however, this configuration is notintended to be limiting as to the scope of the disclosure providedherein since additional connecting elements 154, 155 could also be used.Thus, in this example, the connecting element 155 connects the junction361 to a connection point 246 (FIGS. 2C1-2C2) near the center of thepower distribution element 161. A first connecting element 154 connectsthe junction 361 to a connection point 247 (FIGS. 2C1-2C2) positioned atone edge of the power distribution element, such as the left edge of thepower distribution element 161. A second connecting element 154 connectsthe junction 361 to a connection point 247 (FIGS. 2C1-2C2) positioned atanother edge of the power distribution element, such as the right edgeof the power distribution element 161. In some embodiments, thedistances between the junction 361 and each of the connection points246, 247 are selected to achieve a desirable wave pattern within each ofthe RF power delivery components as they are driven during processing.

In general, the RF generators in the RF source assembly 150 areconfigured to supply RF power (voltage and/or current) to the electrodeassembly 160 components. An output impedance of the RF generator 351 ismatched via the matching network 355 to the impedance of the loadedtransmission line system 190 to efficiently transfer power from the RFgenerator 351 to the loaded transmission line system 190. The matchingnetwork 355 is thus configured to provide a desired forward andreflected RF power based on the driven frequency provided from the RFgenerator during processing. In some embodiments, the RF power providedby the RF generators is provided in a range between about 50 kilohertz(kHz) and about 3 gigahertz (GHz). It has been found that the electrodeassembly configuration(s) described herein are especially useful inconfigurations where the RF power is applied at frequencies greater thanor equal to 13.56 MHz, such as RF power provided in the VHF range (30MHz to 300 MHz) or UHF range (300 MHz to 3 GHz). Higher frequency RFpower in the VHF or UHF range is advantageously used to provide higherplasma densities at a lower drive voltage than a lower RF frequencywould provide. Use of lower drive voltages can be important to preventor minimize the risk of arcing, which cause damage to the substratesthat are being processed in the process chamber, as the plasma densityis increased when using a CCP source configuration. Use of a lower drivevoltage can also provide a reduced ion energy and/or narrower ion energydistribution in the generated plasma, which can provide improved processresults and reduced substrate damage during processing of certainsemiconductor device structures formed on the substrate surface.

During operation, the RF power provided to each of the connection points246, 247 causes RF waves (voltage/and or current) to travel from thecenter to the edges, from the edges to the center and from edge to edgewithin the power distribution element 161. The transmitted wavesconstructively and destructively interfere with each other and in thesteady state can in some cases generate standing waves with peaks andtroughs at different positions along the power distribution element 161and along the conducting rods 166 that are connected to the powerdistribution element 161. The pattern of peaks and troughs of thestanding wave(s) on the power distribution element 161 and along theconducting rods 166 are an important contributor to plasmanon-uniformity and relative changes in plasma density across the surface226 of the lid assembly 200. In some applications, the interfering wavepatterns created by the delivery of RF power from a single source, suchas RF generator 351 and a matching network 355, may provide acceptablepower distribution uniformity at the tips of the conductive rods 166 sothat an acceptable plasma uniformity within the processing region 110can be generated. However, in other applications, the physicalconfiguration of the electrode assembly 160 components may be less thanadequate, since the position and amplitude of the wave patterns is notuniform and is not easily altered by adjusting the electricalcharacteristics of the RF power delivered to the electrode assembly 160components or replacement and/or reconfiguration of the physicalelectrode assembly 160 components.

FIG. 4B is a schematic depicting an embodiment of the RF source assembly150 that includes the RF generator 351 illustrated in FIG. 4A and anadditional RF generator 357. The RF generator 351 and RF generator 357are both configured to provide RF power to the matching network 355,connecting elements 154, 155 and the electrode assembly 160. In oneembodiment, the RF generator 357 is configured to deliver RF power at afrequency that is different from the frequency of the RF power providedby the RF generator 351. The matching network 355 is configured toprovide a match at the two different RF frequencies provided by the twoRF generators. In some embodiments, the frequency differences of the RFpower provided by the RF generator 351 and the RF generator 357 aresignificantly different, such as tens or a hundred megahertz apart. Inone example, the RF generator 351 is configured to provide RF power at13.56 MHz and the RF generator 357 is configured to provide RF power at2 MHz. In one embodiment, the RF generator 351 is configured to provideRF power at a first UHF or VHF frequency and the RF generator 357 isconfigured to provide RF power at frequency below a VHF frequency. Inone example, the RF generator 351 is configured to provide RF power at60 MHz and the RF generator 357 is configured to provide RF power at 2MHz. In another example, the RF generator 351 is configured to provideRF power at 162 MHz and the RF generator 357 is configured to provide RFpower at 13.56 MHz.

FIG. 5A is a schematic depicting an embodiment of the RF source assembly150 for driving the plurality of discrete electrodes 165 so as toprovide a desired plasma uniformity within the processing region 110.The RF delivery assembly in this embodiment includes an RF signalgenerator 530, a phase shifter 531, a phase controller 520, a first RFgenerator 532 and a second RF generator 533, a first three-portcirculator 471 with a dummy load 475 and a second three-port circulator472 with a dummy load 476, a first matching network 534, a secondmatching network 535, and a phase detector 525.

In this configuration of the RF source assembly 150, the RF signalgenerator 530 is connected to the input of the phase shifter 531 tosupply a phase-shift control signal to at least one of the RFgenerators, such as RF generator 532 as shown in FIG. 5A. The phaseshifter 531 receives a control signal from the phase controller 520 toadjust the phase of the phase-shifted signal. In one example, a singlefixed choice of phase difference for a specific hardware configurationand plasma load condition may provide a standing wave pattern and VSWR(voltage standing wave ratio) that has an associated acceptable level ofnon-uniformity. In one embodiment, the phase set point is modulated overtime by adjusting the control signal generated by the phase controller320 to form a uniform standing wave pattern and lower VSWR, and thuscreate a more desirable level of plasma non-uniformity and desirableprocess results. In some configurations, the control signal generated bythe phase controller 320 is modulated between a lower limit and an upperlimit by use a modulating function (e.g., linear, non-linear, timeweighting function) to better control the level of plasma non-uniformityand plasma process results.

Each of the three-port circulators 471, 472, or circulators 471, 472,has a first port that receives the RF power delivered, respectively,from an RF generator 532, 533 and transfers the received RF power to asecond port, which transmits the RF power to a matching network 534,535. The third port of each circulator is connected to a dummy load 475,476 to which any power received by the second port, such as reflectedpower or power received from the opposing RF generator, is provided. Thedummy loads 475, 476 include resistive, inductive and/or capacitivecircuit elements that have a desired impedance, and thus in some casesmay include a 50Ω load, which is typically predominantly resistive innature.

The first matching network 534 transmits, via the connecting element155, RF power received from the first circulator 471 to a point near thecenter of the power distribution element 161. The second matchingnetwork 535 transmits, via connecting elements 154, RF power receivedfrom the second circulator 472 to edges of the power distributionelement 161. Thus, the first and second matching networks 534, 535respectively couple the RF generators 532, 533 and first and secondcirculators 471, 472 to the power distribution element 161 and thusprovide a match between the impedance of the RF generators 532, 533 andcirculators 471, 472 and the driven load(s), such as impedances 365.

The first and second matching networks 534, 535 may receive power thatis reflected from the components in the electrode assembly 160. Some ofthis reflected power may be transmitted through the first and secondmatching networks 534, 535 to the second ports of the first circulator471 and the second circulator 472, respectively. This power is thentransferred by each of the first and second circulators 471, 472 to therespective dummy loads 475, 476 connected on the third ports of eachcirculator 471, 472.

Connected between the output of each matching network 534, 535 is thephase detector 525, which detects a difference in phase between the RFoutput (i.e., current, voltage or power) of each matching network 534,535. The phase detector 525 may include a detector that is configured todirectly measure the difference in the phase of the RF power output fromthe RF generators 532, 533. Alternately, the phase detector 525 mayinclude a detection assembly that has individual sensors that areconfigured to detect the phase of the RF power provided from an RFgenerator 532, 533 and then has the capability to calculate thedifference in the relative phase of the RF power output from the RFgenerators 532, 533 from the two signals provided by the individualsensors. A signal representing the detected phase difference is suppliedto the phase controller 520, which in turn provides a signal to thecontrol input of the phase shifter 531 which provides a control signalto an input of the first RF generators 532 to alter the relative phaseof the RF power provided from the first RF generators 532 relative tothe RF power provided from the second RF generators 533. This causes theRF power provided by each matching network 534, 535 to the powerdistribution element 161 to have a phase difference that is set by thephase shifter 531.

In operation, the RF power applied to the edges of the powerdistribution element 161 differs in phase from that of the RF powerapplied to the approximate center of the power distribution element 161.As discussed above, the RF wave emitted from the first matching network534 and the RF wave emitted from the second matching network 535 traveltowards each other and interfere constructively and destructively,resulting in what can be viewed as a standing wave on the powerdistribution element 161 in the steady state. However, in thisembodiment, the phase controller 520 can alter the detected phasedifference between the two waves, thereby altering the positions of thepeaks and troughs of the generated standing wave on the powerdistribution element 161. By selectively positioning of the peaks andtroughs or varying the position of the peaks and troughs over timewithin one or more of the RF transmission components and conductive rods166 found within the electrode assembly 160, more uniformity of theplasma can be achieved.

In some embodiments, the phase of the RF power applied to the edges andapproximate center of the power distribution element 161 can becontinuously modulated by the phase controller 520 so that the timeaverage of the RF power provided on the power distribution element 161is more uniform as compared to any selected phase setting or set ofselected phase settings provided by the phase controller. In oneembodiment, the modulation rate is 100 Hz and in another embodiment, therate is 10,000 Hz. In one example, the modulation rate is set betweenabout 1 kHz and 10 kHz.

Additional control of the standing wave on the power distributionelement 161 is possible by modifying the amplitude of the RF powerapplied to the edges and approximate center of the power distributionelement to thus further improving plasma 111 and process uniformity. Insome embodiments, a deliberately non-uniform center to edge RF powerdistribution across the power distribution element 161 can be used for aparticular phase or phase range.

FIG. 5B is a schematic depicting an embodiment of the RF source assembly150 in which an additional RF generator assembly 590 has been added tothe RF delivery components shown in FIG. 5A. The additional RF generatorassembly 590 may be coupled to one of the connecting elements 154, 155so that RF power can be additionally provided to the electrode assembly160 at a frequency that is different from the frequency that is providedfrom the other connected RF generators 451 and 452, respectively. In oneembodiment, the RF generator assembly 590 includes an RF generator 592and a match 593, which is configured to provide a match at the RFfrequency delivered from the RF generator 592. In one example, asillustrated in FIG. 5B, the RF generator assembly 590 is configured todeliver RF power at a frequency that is different from the frequency ofthe RF power provided by the RF generator 451. The frequency differencesof the RF power provided by the RF generator 592 and the RF generator451 may be significantly different, such as tens or about a hundredmegahertz apart. In one embodiment, the RF generators 451 and 452 areconfigured to provide RF power at 13.56 MHz and the RF generator 592 isconfigured to provide RF power at 2 MHz. In another embodiment, the RFgenerators 451, 452 are configured to provide RF power a first UHF orVHF frequency and the RF generator 592 is configured to provide RF powerat frequency below a VHF frequency. In one example, the RF generators451, 452 are configured to provide RF power at 60 MHz and the RFgenerator 592 is configured to provide RF power at 2 MHz. In anotherexample, the RF generators 451, 452 are configured to provide RF powerat 162 MHz and the RF generator 592 is configured to provide RF power at13.56 MHz. To avoid possibly damaging one or more of the components inthe RF source assembly 150, filters 596 and 597 (e.g., high passfilters) may be used to isolate any of the components upstream of thefilters from the RF power provided at the frequency delivered from theRF generator assembly 590.

FIG. 6A depicts a system for driving a plurality of discrete electrodes,in another embodiment of the disclosure provided herein. This embodimentincludes first and second RF signal generators 451, 452, first andsecond circulators 471, 472, each with a dummy load 475, 476, first andsecond matching networks 455, 456, a loaded transmission line system 190representing the plurality of discrete electrodes 165, the powerdistribution element 161 and the reference ground.

In this embodiment, the first RF generator 451 is connected to the firstport of the first circulator 471 and the first matching network 455 isconnected to the second port of the circulator. The first matchingnetwork 455 matches the second port of the circulator 471 to thetransmission line system 190. The circulator 471 also transfers anyreflected or received RF power to the dummy load 475 connected to thethird port of the circulator 472. The second RF generator 452 isconnected to the first port of the second circulator 472 and the secondport of the circulator 472 is connected to the second matching network456. The second matching network 456 matches the second port of thecirculator 472 to the transmission line system 190. The circulator 472also transfers any reflected or received RF power to the dummy load 476connected to the third port of the circulator 472. In some embodiments,the second RF generator 452 is operated at a frequency that is differentfrom the frequency of the first RF generator 451. In one example, thedifference in frequency is between about 1 kHz and 10 MHz, such asbetween about 0.01 MHz and 2 MHz, or even between about 0.01 MHz and 0.5MHz, or even between about 1 kHz and 100 kHz. For example, the first RFgenerator 451 is operated at a frequency of 59.9 MHz and the second RFgenerator 452 is operated at a frequency of 60.1 MHz.

In operation, the first matching network 455 transmits RF power to anapproximately central point on the power distribution element 161 viaconnecting element 155. This establishes an RF wave with the firstfrequency traveling from the approximate center to the edges of thepower distribution element 161. As the RF wave provided at the firstfrequency travels along the power distribution element 161, it deliversa portion of its energy to the plasma 111 through the conductive rods166 and electrode shields 168. The remaining portion of the deliveredpower is transferred to the second matching network 456. At this point,any energy that passes through the second matching network 456 isprovided to the reference ground, and any reflected RF power arrives atthe second port of the second circulator 472 and is transferred to thethird port and absorbed in the dummy load 476 connected to the thirdport of the circulator 472. Similar to the first matching network, thesecond matching network 456 transmits RF power to the edges of the powerdistribution element 161. This establishes an RF wave having the secondfrequency traveling from the edges to the other edges of the powerdistribution element 161 and delivering a portion of its power to theplasma. RF power at the second frequency then reaches the first matchingnetwork 455 and any power that passes through the first matching network455 arrives at the second port of the first circulator 471, istransferred to its third port and absorbed by its dummy load 475.

In this configuration, two traveling waves of different frequenciestraverse the components found in the electrode assembly 160 (e.g., powerdistribution element 161) in opposite directions and thus minimallyconstructively and destructively interfere. Thus, it is believed that byadjusting the RF power characteristics provided to different portions ofthe electrode assembly 160 the uniformity of the plasma 111 generated inthe processing region 110 will be improved.

In some embodiments, a first travelling wave is launched from the firstRF generator 451 through circulator 471 and matching network 455 is atleast partially transmitted (e.g. not completely reflected) into a firstconnection point on the power distribution element 161 and travelsacross the power distribution element 161. The first travelling wavedeposits at least some RF power into the plasma and at least a portionof the RF power (e.g. not completed reflected) flows out of a secondconnection point on the power distribution element 161. The portion ofthe RF power received at the second connection point is at leastpartially transmitted into the second matching network 456 and ispartially absorbed in the resistance of the dummy load 476. Analogously,a second travelling wave launched from the second RF generator 452through circulator 472 and second matching network 456 is at leastpartially transmitted (e.g. not completely reflected) into the secondconnection point and travels across the power distribution element 161.The second travelling wave deposits at least some RF power into theplasma and at least a portion of the RF power (e.g. not completedreflected) flows out of the first connection point. The portion of theRF power received at the first connection point is provided into thefirst matching network 455 and is partially absorbed in the resistanceof the dummy load 475. Therefore, in one or more embodiments of thedisclosure provided herein, these types of methods and hardwareconfigurations (e.g., FIGS. 5A-7A) can be used to at least predominantlyform travelling waves versus forming standing waves.

FIG. 6B is a schematic depicting an embodiment of the RF source assembly150 in which an additional RF generator assembly 620 has been added tothe RF delivery components shown in FIG. 6A. The additional RF generatorassembly 620 may be coupled to one of the connecting elements 154, 155so that RF power can be additionally provided to the electrode assembly160 at a frequency that is different from the frequency that is providedfrom both of the other connected RF generator 451 or 452. In oneembodiment, the RF assembly 620 includes an RF generator 622 and a match621, which is configured to provide a match at the RF frequencydelivered from the RF generator 622. The frequency differences of the RFpower provided by the RF generator 622 and the RF generators 451 and 452may be significantly different, such as tens or a hundred megahertzapart. In one example, the RF generators 451 and 452 are configured toprovide RF power at a frequency greater than or equal to 13.56 MHz andthe RF generator 622 is configured to provide RF power at 2 MHz. In oneembodiment, the RF generators 451, 452 are configured to provide RFpower a first and a second UHF or VHF frequency and the RF generator 622is configured to provide RF power at frequency below a VHF frequency. Inone example, the RF generators 451, 452 are configured to provide RFpower at frequencies near 60 MHz and the RF generator 622 is configuredto provide RF power at 2 MHz. In another example, the RF generators 451,452 are configured to provide RF power at frequencies near 162 MHz andthe RF generator 622 is configured to provide RF power at 13.56 MHz. Toavoid possibly damaging one or more of the components in the RF sourceassembly 150, filters 631 and 632 (e.g., high pass filters) may be usedto isolate any of the components upstream of the filters from the RFpower provided at the frequency delivered from the RF generator assembly620.

FIG. 7A depicts a system for driving a plurality of discrete electrodes,in another embodiment of the disclosure provided herein. This embodimentincludes an RF generator 612, a driving component 617 that includes acirculator 614 with a dummy load 615 and a first matching network 611and a circuit element 618 that includes a second matching network 321with a dummy load 616. The RF generator 612 provides the RF signal tothe first port of the circulator 614 whose second port provides power tothe first matching network 611. The output of the first matching network611 is connected to an edge 161A of the power distribution element toprovide a transmitted wave to the power distribution element 161. Thesecond matching network 321 is connected to another edge 161B of thepower distribution element, which is terminated in a dummy load 616. Thesecond matching network 321 could also be connected to a positionbetween an opposing or different edge and the center of the powerdistribution element 161.

In operation, the first matching network 611 launches a primarytraveling RF wave on the power distribution element 161 from the edge161A to which it is connected. The primary wave traverses the powerdistribution element 161 in one direction to another edge 161B andarrives at the second matching network 321. Any power that passesthrough the second matching network 321 is absorbed by the dummy load616. Thus, as the impedance matching between the first matching network611 and the load (e.g., impedances 365) may not be perfect, power thatwould normally be reflected into the second port of the first circulator471 is lessened or eliminated by use of the additional matching network.

In some configurations, a wave launched from the RF generator 612through circulator 614 and first matching network 611 is at leastpartially transmitted (e.g. not completely reflected) into a first port(i.e., edge 161A) of the power distribution element 161. The transmittedwave then travels across the power distribution element 161, deposits atleast some of the transmitted RF power into the plasma and transmits atleast some of the RF power (e.g. not completed reflected) out of thesecond port (i.e., edge 161B) of the power distribution element 161. TheRF power transmitted out of the second port is at least partiallytransmitted into the circuit element 618 and is partially absorbed inthe resistance of the dummy load 616. This driving method, which isenabled by the use of the electrical components illustrated in FIG. 7A(e.g., two opposing matching networks), can provide improved plasmauniformity due to the use of traveling waves coupling power to plasmarather than purely standing waves that are the result of two or moretraveling waves (e.g. forward and reflected waves combining andinterfering) formed by more conventional RF delivery configurations.

FIG. 7B depicts a bottom view of the physical arrangement of a lidassembly 780 that includes an alternate configuration of a powerdistribution element 161. The alternate version of the lid assembly 780and electrode assembly 160 configurations are schematically shown inFIG. 7A. In this view, the inner edge 161B of the power distributionelement 161 and the outer edge 161A of the power distribution element161 are positioned and aligned in a radial orientation relative to thecenter 792 of a carousel 791, which is a substrate supporting devicethat is configured to transport the substrate past the lid assembly 780as it rotates about the about the center 792 during processing. Theplurality of discrete electrodes 165 are distributed in a pattern thatfills the sector region defined by the angular and radial extents of thelid assembly 780. While not shown for clarity of illustration, theprocess chamber walls (not shown) are disposed concentric with andaround the outside edge of the carousel 791, and thus, in this example,the array of discrete electrodes 165 are not symmetrically positionedrelative to the chamber walls or processing region defining components.During processing the driving component 617 (shown in FIG. 7A) receivesa signal from the RF generator 612 and applies it to the powerdistribution element 161 at the edge 161A. The signal travels alongpower distribution element 161 and is received at edge 161B by circuitelement 618 (shown in FIG. 7A). In some embodiments, as illustrated inFIG. 7B, the edge 161A and edge 161B of the power distribution element161 are positioned so that the edge 112A and opposing edge 112B of thesubstrate 112 will pass under the lid assembly 780 and powerdistribution components as the substrate is rotated about the center 792of the carousel 791.

FIG. 8A depicts another system configuration for driving a plurality ofdiscrete electrodes, in another embodiment of the disclosure providedherein. This embodiment includes an RF generator 612, a drivingcomponent 617 that includes an optional circulator 614 with an optionaldummy load 615 and a first matching network 611 that are coupled to thepower distribution element 161 through the center connecting element155, and a circuit element 810 that is coupled between a referenceground and the power distribution element 161 through the fourconnecting elements 154. In some configurations, the circuit element 810may include at least one of a resistor and an electrical reactanceelement, such as an inductor or a capacitor. In one example, the circuitelement 810 includes a resistor, an inductor and a capacitor. In someconfigurations, the circuit element 810 includes a second matchingnetwork 321 and a dummy load 616. The RF generator 612 provides the RFsignal to the first port of the circulator 614 whose second portprovides power to the first matching network 611. The output of thefirst matching network 611 is connected to the center connecting element155 that is coupled to the power distribution element 161 to provide RFpower, which can include a transmitted wave, to the center portion ofthe power distribution element 161. The circuit element 810 is connectedto at least one of the edge connection points of the power distributionelement.

In one operational configuration, the first matching network 611launches a primary traveling RF wave to the center of the powerdistribution element 161. The primary wave traverses the powerdistribution element 161 in an outward direction from the center to edgeof the power distribution element 161 and then arrives at the circuitelement 810. Any power that passes through the circuit element 810 iscan be at least partially absorbed by the resistive elements disposedtherein (e.g., dummy load 616) to control the delivery of RF power tothe processing region. Thus, as the impedance matching between the firstmatching network 611 and the load (e.g., impedances 365) may not beperfect, the power that would normally be reflected into the second portof the first circulator 614 is lessened or eliminated by use of thecomponents within the circuit element 810. In an alternate operationalconfiguration, the impedance of circuit element 810 may be selected toaffect the reflected wave amplitude and/or phase at that location, suchthat the combination of the forward traveling wave and reflectedtraveling wave combine to produce a standing wave, and the standing wavepattern along the power distribution element 161 acts on the pluralityof electrodes to produce a plasma uniformity profile.

FIG. 8B depicts another system configuration for driving a plurality ofdiscrete electrodes 165. This embodiment includes an RF generator 612, adriving component 617 that includes an optional circulator 614 with anoptional dummy load 615 and a first matching network 611 that arecoupled to the power distribution element 161 through at least one ofthe four connecting elements 154, and a circuit element 810 that iscoupled between a reference ground and the power distribution element161 through the center connecting element 155. In some configurations,as discussed above, the circuit element 810 may include at least one ofa resistor and an electrical reactance element, such as an inductor or acapacitor. During processing, the RF generator 612 provides an RF signalto the first port of the circulator 614 whose second port provides powerto the first matching network 611. The output of the first matchingnetwork 611 is connected to the four connecting elements 154 that iscoupled to the power distribution element to provide RF power, which caninclude a transmitted wave, to the edge portion of the powerdistribution element 161. In this configuration, the primary wavetraverses the power distribution element 161 in an inward direction fromthe edge(s) to the center of the power distribution element 161 and thenis transmitted to the circuit element 810. As noted above, any powerthat passes through the circuit element 810 is can be at least partiallyabsorbed by the resistive elements disposed therein (e.g., dummy load616) to control the delivery of RF power to the processing region. In analternate operational configuration, the impedance of circuit element810 may be selected to affect the reflected wave amplitude and/or phaseat that location, such that the combination of the forward travelingwave and reflected traveling wave combine to produce a standing wave,and the standing wave pattern along the power distribution element 161acts on the plurality of electrodes to produce a plasma uniformityprofile.

Thus, embodiments of the disclosure may provide an upper chamberassembly that includes a lid assembly 200, an electrode assembly 160, anRF source assembly 150, fluid source assembly 180, supporting RF sourceassembly 460 and a lower chamber assembly 30 that interoperate to form aplasma that has desirable plasma properties (e.g., degree ofdissociation, gas composition, radical density or flux, plasma ion andelectron density, electron temperature, ion energy distribution, etc.)due to the controlled and/or uniform delivery of RF power to the processgasses introduced into the processing region of the process chamber. Bycontrolling the uniformity of the RF power provided to the processingregion by the array of discrete electrodes 165, via one or more of theembodiments of the disclosure provided above, and controlling theprocess gas composition and gas properties (e.g., pressure, flow rate,flux, etc.) in the processing region, a plasma having desirable plasmaproperties is achieved.

FIG. 9 is a side cross-sectional view of portions of the lid assembly200 and the electrode assembly 160, which is similar to theconfiguration illustrated in FIG. 2A and discussed above. The electrodeassembly 160 includes a plurality of discrete electrodes 165 that areeach coupled to the RF source assembly 150 through one or more powerdistribution elements 161. However, the process chamber 100 illustratedin FIG. 9 includes a substrate support circuit element 910 that iscoupled between a biasing electrode 464 and a reference ground. In someconfigurations, the substrate support circuit element 910 may include atleast one of a resistor and an electrical reactance element, such as aninductor or a capacitor. In one example, the circuit element 910includes a resistor, an inductor and a capacitor. In someconfigurations, the circuit element 910 includes a second matchingnetwork 321 and a dummy load 616. The circuit element 910 and theelectrode 464 can thus be used in conjunction with the discreteelectrodes 165 to form and/or adjust properties of a plasma 111 formedin the processing region 110. The RF power flowing through the electrode464 to the reference ground can be adjusted by adjusting the impedanceof one or more of the circuit components in the circuit element 910,along with the position of the substrate 112 relative to the discreteelectrodes 165 and/or the RF power provided to the discrete electrodes165, to control the interaction of the formed plasma (e.g., amount ofradical and/or ion interaction) with the exposed surfaces of thesubstrate 112. In one application where it is beneficial to minimize theenergy of ions impacting the exposed surfaces of the substrate 112, theratio of the sum of the surface areas A1 of the discrete electrodes 165to the reference electrode element surface area A2 is selected to benearly 1 (i.e., between 0.8 and 1.2, or preferably between about 0.9 and1.1) and the impedance at the generator frequency from the substrate 112back through electrode 464 to the reference ground is maximized, byselecting a value(s) for circuit element 910. In one configuration, thecircuit element 910 is a filter circuit. In an alternate configuration,the circuit element 910 is a switch or relay that is opened duringcertain steps of plasma processing and closed during other steps. Whileelectrode 464 is schematically shown as a single line in FIG. 9, it isunderstood that electrode 464 may comprise one or more layers ofelectrode, heating element, temperature sensor or other conductivematerial.

In some embodiments, the process chamber 100 may also include an RFswitching device 469 that is disposed between the electrode 464 and thecircuit element 910. The RF switching device 469 may include an RFcoaxial vacuum relay that has high impedance when in its open state anda low impedance in its closed state. The RF switching device 469 can beused to electrically isolate the substrate 112 from ground to minimize,or substantially eliminate, the bombardment of the substrate surface byions generated in the plasma 111 during one or more portions of theplasma process. Bombardment of the substrate surface by the plasmagenerated ions can cause unwanted damage to portions of the substratesurface. During at least a portion of the plasma process performed onthe substrate 112 the RF switching device 469 is set to its open stateto electrically isolate the electrode 464 from ground. The highimpedance electrical characteristics of the RF switching device, such asan impedance of greater than 100 Ohms at the fundamental RF drivefrequency and its harmonic series (e.g., at least the 2^(nd) and 3^(rd)harmonics), allows the substrate 112 and electrode 464 to substantiallyelectrically float while the RF switching device is positioned in itsopen state. One suitable example RF switching device, an RF coaxialrelay, has an open-state capacitance across the contacts of 3 pF, whichat an RF generator drive frequency of 40.68 MHz has an impedance (e.g.,capacitive reactance) of over 1200 ohms.

In some embodiments, during processing a sequentially pulsed RF bias isprovided to the discrete electrodes 165 relative to the referenceelectrode 225B to generate the plasma 111 in the processing region 110.The pulsed RF bias can include an RF “on” state and an RF “off” state,which each have a desired duration. In one plasma processing example,the RF switching device 469 is controlled to its open state when thepulsed RF bias is in the RF “on” state (e.g., RF energy is applied tothe discrete electrodes 165 in the electrode assembly 160). In analternate example, the RF switching device 469 is controlled to its openstate during a portion of the RF “on” state pulses to reduce, but notsubstantially eliminate, the ion bombardment of the substrate surfaceduring plasma processing of the substrate.

In some embodiments, the processing chamber 100 may additionally includeone or more additional RF switching devices that are separately coupledto each of the additional electrical connections formed betweenelectrical elements (e.g., pedestal heater elements (not shown),thermocouple(s) (not shown), etc.) that are coupled to the pedestal 120and their external electrical components (e.g., power supply (notshown), thermocouple board (not shown), etc.). In this configuration,during at least a portion of the plasma process performed on thesubstrate 112, the one or more additional RF switching devices can beset to their open state to allow the pedestal 120 of the supportassembly 115 to be substantially electrically isolated from groundduring processing. Thus, in one plasma processing example, the RFswitching device 469 and all of the additional RF switching devices arecontrolled to their open state when the pulsed RF bias is in the RF “on”state. In another example, the RF switching device 469 and all of theadditional RF switching devices are controlled to their open stateduring a portion of the RF “on” state pulses to reduce, but notsubstantially eliminate, the ion bombardment of the substrate surface.

In some embodiments, the process chamber 100 may include one or more RFfilters that are used to prevent the electrical elements (e.g., pedestalheater elements, thermocouple(s), etc.), which are coupled to portionsof the pedestal 120 of the support assembly 115, from electricallygrounding the support assembly 115.

In one example, one or more process gases are provided from theplurality of distribution channels 283 formed in the lid assembly 200and into the processing region 110 of the process chamber 100 that ismaintained at a vacuum pressure (e.g., 0.1 milliTorr to 200 Torr) by useof one or more gas delivery components found in one or more of the gassources 243 and lower chamber assembly 30 components. In someconfigurations, the process chamber 100 is maintained at a vacuumpressure of between 0.1 mTorr and a 100 mTorr. The one or more processgases include gases that enable the completion of the desired plasmaprocess that is to be performed on a substrate 112 that is disposed onthe surface of the support assembly 115 during processing, and mayinclude deposition process gases (e.g., precursor gases and carrier gas)or etching process gases (e.g., dry etching gases and carrier gases).The temperature of the process gases that are provided into theprocessing region 110 may also be adjusted by controlling thetemperature of the lid assembly 200 components by use of the temperaturecontrol system that is described above. Once a desired gas flow rate,gas pressure and/or flow distribution is achieved in the processingregion 110, the components in the RF source assembly 150 are used tocontrol the uniformity of the RF power provided to the array discreteelectrodes 165, via one or more of the embodiments of the disclosureprovided above. The RF bias provided to the discrete electrodes 165relative to the reference electrode 225B (e.g., reference electrodeelement 225A, chamber walls and/or interleaved grounded conductive rods166) generates a plasma 111 in the processing region 110 and theuniformity of the plasma is enhanced by phase control, amplitude controland/or frequency control of RF waves provided over the powerdistribution element 161 and discrete electrodes 165 according to thevarious embodiments disclosed herein. As discussed above in conjunctionwith FIGS. 2G-2H, it is believed that positioning a reference electrodeelement 225A proximate to the discrete electrodes 165 can provide animproved plasma uniformity across the surface 226 of the lid assembly200 in configurations where the process chamber walls (e.g., chamberside walls 405, chamber floor 410) are not symmetrically positionedaround the discrete electrodes 165 and lid assembly 200, such as theprocess chamber configuration illustrated in FIG. 7B. In someembodiments, the configuration of the array of discrete electrodes 165and the distance that the ends of the discrete electrodes 165 aredisposed above or below the surface 226 of the lid assembly 200 and/orreference electrode element 225A are also selected or adjusted tofurther improve the generated plasma properties. In this manner, theresulting plasma density and uniformity and radical generation anddensity are better controlled.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

The invention claimed is:
 1. A plasma source assembly, comprising: areference electrode having an electrode surface, wherein the electrodesurface has a central axis that is perpendicular to the electrodesurface at a center point; and an array of discrete electrodes that arearranged in a pattern that is distributed in at least two non-paralleldirections that are both substantially parallel to a first plane, whichis oriented in a perpendicular orientation to the central axis, wherein:each of the discrete electrodes have a length that is aligned parallelto a first direction that is oriented at an angle greater than zero tothe first plane, and each of the discrete electrodes includes an endthat is disposed a distance from the electrode surface, wherein thedistance is measured in a direction that is perpendicular to the firstplane.
 2. The plasma source assembly of claim 1, wherein at least aportion of each of the discrete electrodes in the array of discreteelectrodes extends through an opening formed through the referenceelectrode.
 3. The plasma source assembly of claim 2, wherein at least aportion of the reference electrode surrounds each of the discreteelectrodes in the array of discrete electrodes.
 4. The plasma sourceassembly of claim 1, wherein: each of the discrete electrodes has anouter surface that has a discrete electrode surface area that comprisesan area of the outer surface disposed from the end of the discreteelectrode to the electrode surface of the reference electrode; theelectrode surface has a reference electrode surface area; and a ratio ofthe sum of all of the discrete electrode surface areas to the referenceelectrode surface area is between 0.8 and 1.2.
 5. The plasma sourceassembly of claim 1, wherein the electrode surface is planar.
 6. Theplasma source assembly of claim 1, further comprising: a perforatedplate having a plurality of openings formed through a perforated surfaceof the perforated plate, wherein the plurality of openings are arrangedin a pattern that is configured to provide a desired gas flowdistribution across the perforated surface when a gas is deliveredthrough the plurality of openings, and wherein the electrode surface isparallel to the perforated surface of the perforated plate.
 7. Theplasma source assembly of claim 6, wherein the perforated platecomprises a material selected from a group consisting of silicon,silicon carbide, alumina, yttria, zirconia, silicon nitride, graphite,aluminum nitride and silicon dioxide.
 8. The plasma source assembly ofclaim 1, wherein the distance of each of the discrete electrode ends isbetween −10 mm and 20 mm.
 9. The plasma source assembly of claim 1,wherein each of the discrete electrodes within the array of discreteelectrodes comprises a conductive rod that is disposed within anelectrode shield.
 10. The plasma source assembly of claim 9, wherein theelectrode shield comprises a dielectric or semiconducting material thatis selected from a group consisting of sapphire, silicon, siliconcarbide, alumina, yttria, zirconia, aluminum nitride and silicondioxide.
 11. The plasma source assembly of claim 1, wherein each of thediscrete electrodes within the array of discrete electrodes comprises aconductive rod that is disposed within an electrode shield thatcomprises a dielectric or semiconducting material, and wherein: aportion of an outer surface of the electrode shield in each of thediscrete electrodes defines the end of the discrete electrode; and thedistance of each of the discrete electrode ends is between −10 mm and 20mm.
 12. The plasma source assembly of claim 1, wherein each of thediscrete electrodes within the array of discrete electrodes comprises aconductive rod that is disposed within an electrode shield and iscoupled to a power distribution plate, and wherein the plasma sourcefurther comprises an RF distribution system that transfers RF power toeach of the conductive rods by delivering RF power to at least twodifferent points on a surface of the power distribution plate.
 13. Aplasma source assembly, comprising: a reference electrode having anelectrode surface, wherein the reference electrode is coupled to aground; a power distribution element connected to a plurality ofdiscrete electrodes, wherein the discrete electrodes are arranged in apattern that is distributed in at least two non-parallel directions thatare both parallel to an outer surface of the plasma source assembly, andeach of the discrete electrodes includes an end that is disposed a firstdistance from the outer surface in a direction that is perpendicular tothe outer surface; an RF signal generator that is configured to provideRF power to a first connection point on the power distribution element;and a circuit element that comprises one or more electrical reactanceelements and is configured to allow a current to flow from a secondconnection point on the power distribution element to the ground. 14.The plasma source assembly of claim 13, wherein the RF signal generatoris configured to generate RF power at a first frequency, and the plasmasource assembly further comprises: a pedestal having a substratesupporting surface for supporting a substrate during processing, whereinthe substrate supporting surface has an electrical impedance magnitudeto ground, at the first frequency, that is greater than 100 ohms. 15.The plasma source assembly of claim 14, wherein: each of the discreteelectrodes has an outer surface that has a discrete electrode surfacearea that comprises an area of the outer surface disposed from the endof the discrete electrode to the electrode surface of the referenceelectrode; the electrode surface has a reference electrode surface area;and a ratio of the sum of all of the discrete electrode surface areas tothe reference electrode surface area is between 0.8 and 1.2.
 16. Theplasma source assembly of claim 13, wherein each of the discreteelectrodes within the array of discrete electrodes comprises aconductive rod that is disposed within a dielectric or semiconductingmaterial containing electrode shield, and each of the conductive rodshave a length that is aligned along the direction that is perpendicularto the surface.
 17. The plasma source assembly of claim 16, wherein eachof the discrete electrodes within the array of discrete electrodescomprises a conductive rod that is disposed within an electrode shieldthat comprises a dielectric or semiconducting material, and wherein: aportion of an outer surface of the electrode shield in each of thediscrete electrodes has an end; the end of the electrode shield isdisposed a distance from the electrode surface, wherein the distance ismeasured in a direction that is perpendicular to the first plane; andthe distance of each of the ends of the electrode shields is between −10mm and 20 mm.
 18. A plasma source assembly, comprising: a referenceelectrode having an electrode surface, wherein the electrode surface hasa central axis that is perpendicular to the electrode surface at acenter point; and an array of discrete electrodes that are arranged in aspaced apart pattern that is parallel to a first plane, which isperpendicular to the central axis, wherein each of the discreteelectrodes comprise a conductive rod that has a first end, a second endand a body disposed between the first end and the second end, whereinthe body is aligned parallel to a first direction that is oriented at anangle greater than zero to the first plane, and each of the discreteelectrodes includes an end that is disposed a distance from theelectrode surface, wherein the distance is measured in a direction thatis perpendicular to the first plane.
 19. The plasma source assembly ofclaim 18, wherein at least a portion of each of the discrete electrodesin the array of discrete electrodes extends through an opening formedthrough the reference electrode, and at least a portion of the referenceelectrode surrounds each of the discrete electrodes in the array ofdiscrete electrodes.
 20. The plasma source assembly of claim 18, furthercomprising a power distribution element coupled to the discreteelectrodes, wherein the power distribution element is a conductive platewith a plurality of slots formed through the conductive plate, whereinthe plurality of slots are configured to limit current flow betweenadjacent regions of the conductive plate.